Tribal Sister and avid follower Christy sent me this a while back –
Can you enlighten me about ratios/proportions in a dish I make? I frequently make a chile rellenos casserole because I have lots of poblanos and it’s an easy dish that can be spicey or mild. Every time I look at various recipes I can never decide what I should do about ratios in the egg-milk part. Basically, it’s a layer of poblano, topped with a protein, cheese and then covered with a mix of eggs, milk, and flour. Sometimes baking powder is added and usually additional cheese is added to the mixture before pouring over. I am looking for that sweet spot where it’s not too eggy–not a quiche or frittata–but not too watery. The poblanos need to shine through. Maybe you can explain the dynamics of this to me so I can fix some proportions in my mind – an inquiring mind wishes to know!
Chris further related that the ratios she’d found varied from 1/2 cups to 2 cup of milk, anywhere from 2 to 8 eggs, and 2 tablespoons to 1/2 cup of flour – She happens to be a Phd Archeologist and a hell of a fine cook, so no wonder that wild a statistical swing rocked her boat a bit!
I gave her letter another read, and doing so revealed more problems with this potential recipe than just the egg/milk ratio. I’ve made plenty of rellenos in several regional styles, but had never tackled relleno casserole, so naturally, I was hooked. What followed was an interesting lesson in recipe development that I thought would be fun to share here.
The exercise begins with the problem Chris wants fixed – 1. what ratio of egg/milk/flour will yield a relleno casserole that most closely duplicates a solo relleno, and 2. One that’s not too watery, and 3. one that lets the chile be foremost in the taste profile.
Next comes the further issues I identified in her notes, namely – 1. Why are some cooks adding baking powder, and 2. Why is the egg/milk/flour mixture being added last? Those two things needed to be thought out and addressed as well.
A look at a bunch of recipes revealed exactly what frustrates Chris – All over the place, and generally very eggy – way more of a frittata/quiche-like thing than any relleno variant I’m aware of. Why that happens is anyone’s guess – either preference or an assumption that things need to be done that way to work out, is mine.
To decide what to do took some reflection on the parent dish, the noble chile relleno. While there are variations in filling and coating, one thing remains true – Virtually all variations honor the chile and make it forward in the overall taste profile of the dish. Fillings might be anything from just cheese, to meat, meat and cheese, veggies, and combinations thereof.
Rellenos are shallow fried, and coatings vary from none to fairly fluffy mixes reminiscent of tempura. In between, you might find just egg and cornmeal, egg and flour, and the well known three stage dredge of egg/milk/flour. The fluffy coating variants explain where the baking powder option in some casseroles comes from – it’s deployed to help produce a light and airy coating – as such, it really has no place in a casserole – it’s not going to do what it’s intended to in this dish.
Next question for me was, is some form of egg/milk/flour mix necessary? My immediate answer was yes, because there is a place for the flavor note, and maybe just a hint of crunch that a proper mix and volume would offer, if deployed properly – and pouring whatever coating mix is used on top of a casserole is not the right place to deploy it. What that leads to is permeating everything throughout the casserole with an eggy mix, yielding exactly what Chris and I don’t want.
The coating mix should be on the bottom of the dish, where direct and latent heat will allow a thin layer to crisp up a bit, emulating the solo relleno. And the rest of the mix should go atop of the poblano layers, right where it should be for taste and effect, and about midway through the casserole. Finally, the volume of coating mix shouldn’t be excessive – it should be just enough to coat the poblanos.
As for watery casserole, the culprit there is going to be meat and veggies that don’t get properly prepared to work in the dish – the poblanos need to be thoroughly blistered, which does take appreciable moisture out of them without drying them out. Any other veggies need to be sautéed long enough to reduce their moisture content as well. I think milk of any kind will add too much water to the mix, so issued cream. Eggs needs to be fresh, or they too will add excess moisture. Finally, crappy chorizo and/or cheese will add water to the mix, so avoid those outright.
So, what else to put in there? To me, just meat, cheese and chiles is kinda pedestrian in a casserole – I want veggies, too. I settled on onion, garlic, some hot chiles, and tomato – all of those show up in various relleno recipes, so they’re spot on here, too.
Initially, I told Chris I was going to think of the proper ratio as a gravy, and as fate would have it, that was wrong. Working this recipe up to the point where everyone in the house said ‘damn,’ and the leftovers were better than the first night took three tries to get right.
The first swing suffered from too much batter, and lousy chorizo. The second one was OK, but watery – it suffered from old poblanos, and too much water in the veggie mix. All this was solved in v. 3.0 with fresh, local chorizo seco, proper pre-sautéing of most of the veggie mix, and physically squeezing excess juice out of the fresh tomatoes.
For chorizo seco, (the drier, often spicier cousin of the regular stuff), and good Mexican cheeses, (I used a 50%-50% blend of Oaxaca and Asadero cheeses for the dish), I’ll bet dimes to dollars there’s a good Latin grocery or two near you. If that’s not the case, I’ll recommend 90%-10% ground beef with homemade chorizo seasoning, (also provided herein) – that’ll give you the flavor without excess grease. For cheese, I’d go with 50%-50% Monterey Jack and Sharp Cheddar. Finally, your poblanos gotta be fat and sassy – a thick, juicy chile is an absolute must for this dish.

Urban’s Chile Relleno Casserole
5-6 large, fresh Poblano Chiles
1 Pound fresh Chorizo Seco (or alternative- see above)
1 Pound Melting Cheese Blend, (see above)
1 small yellow Onion
2-3 hot Chiles (Jalapeño, Fresno, or Serrano)
3 cloves fresh Garlic
1 teaspoon Mexican Oregano
2 Roma Tomatoes
1/2 Cup 1/2 & 1/2
2 Eggs
2 Tablespoons All Purpose Flour
1 Tablespoon Avocado Oil
Kosher Salt
Ground Black Pepper

Place poblanos on a baking pan under a broiler, 2 rack spots from top.
Blister poblanos, turning regularly to make sure they’re evenly seared.
Remove from oven and allow to cool enough to handle.
Peel, end trim and dice 1 packed cup of onion and the hot chiles.
Peel, end trim and mince garlic.
Slice tomatoes in half, end trim, gut, and dice.
Uncase chorizo, or prep alt. beef (see below for seasoning)

Grate cheeses and combine.
Combine cream, eggs and flour in a small mixing bowl, and whisk vigorously to fully incorporate.
In a sauté pan over medium heat, add a tablespoon of avocado oil and allow to heat through. Add onion, hot chiles, garlic, and oregano, a pinch of salt and a few twists of pepper.

Sauté until onions start to turn translucent, about 3-4 minutes. Remove veggie mix from heat and transfer to a small mixing bowl to cool.
Gently remove blistered skins from poblanos, then cut poblanos in half down the natural sides, leaving nice big slabs of chile.

In sauté pan over medium heat, add chorizo or beef and sauté, stirring steadily, until roughly 3/4 cooked through. If you’re using beef, add 2-4 tablespoons of chorizo seasoning to 1 pound of beef and cook. Transfer to a mixing bowl, discarding any excess liquid.

Set up your mise en place in prep for assembly.

Preheat oven to 350° F and set a rack with a baking sheet in the middle slot.
In a large casserole dish (9” x 11” or thereabouts), pour a thin layer of the coating mix, and swirl to evenly cover the bottom of the dish.

Lay down a solid layer of poblanos over the coating mix.
Add the chorizo or beef and spread in an even layer.

Add about half the cheese blend and spread evenly.

Add second layer of poblanos, covering completely.

Pour the rest of the coating mix onto the second poblano layer, to even;y cover the filling.

Add the sautéed veggies and spread evenly.

Hand squeeze any excess juice out of the diced tomatoes, and spread evenly.
Add the rest of the cheese blend and spread evenly.

Bake at 350° for 45 minutes, until topping cheese is bubbling and nicely browned.

Remove from oven and allow to rest for 10 minutes.
Serve over a bed of cabbage and lettuce, and maybe a few other renegade veggies, with ice cold cerveza Mexicana, and maybe some fresh tortilla chips to chase the naughty bits with.

Urban’s Go To Mexican Chorizo Seasoning
2 Tablespoons Granulated Garlic
2 Tablespoons Red Hatch Chile Powder
1 Tablespoon Smoked Paprika
2 teaspoons Sweet Paprika
2 teaspoons Mexican Oregano
2 teaspoons Smoked Salt
1 teaspoon Cumin Seed
1 teaspoon ground Black Pepper
Grind any and all whole spices to a smooth powder, then combine all ingredients.
Store in clean glass with a airtight lid, out of direct sunlight.