Pour the mayonnaise and Mexican crema into a medium mixing bowl and whisk until completely combined. The creamy base should be smooth with no streaks of either ingredient remaining. Now stir in the Tajín seasoning until the mixture becomes a uniform pale yellow-orange color. Squeeze the fresh lime juice directly into the bowl and whisk again. The sauce will taste intensely tangy at this point—this is correct. Now add the milk one tablespoon at a time, whisking thoroughly after each addition, until you reach a consistency that's pourable but still clings slightly to a spoon. Taste and add a pinch of sea salt if needed. Set the bowl aside in the refrigerator while you prepare the other components.

Remove the chicken breasts from packaging and pat them completely dry with paper towels. Place one breast on a cutting board and, using a sharp chef's knife, carefully slice horizontally through the middle of the breast, creating two thin filets of approximately equal thickness. This technique—called butterflying—is what restaurants use because it cuts cooking time in half and ensures no dry edges. Repeat with the remaining breasts. You should have four thin filets. Combine the chili powder, cumin, paprika, garlic powder, oregano, salt, and pepper in a small bowl. Sprinkle this mixture generously on both sides of each chicken filet, patting it gently so the spices adhere. Don't be shy with the seasoning—this is where the restaurant flavor comes from.

Heat a large skillet (cast iron or stainless steel, 12-inch works best) over medium-high heat for 2 minutes. Add the olive oil and let it shimmer—when it moves easily around the pan, it's ready. Carefully lay the chicken filets in the hot oil without overcrowding. You may need to work in batches. Let each filet cook undisturbed for 4-5 minutes until the underside develops a golden-brown crust. Flip each filet and cook the other side for another 4-5 minutes. The internal temperature should reach 165°F when measured with an instant-read thermometer at the thickest part. Transfer the cooked chicken to a clean plate and tent loosely with foil to keep warm.

Don't wash the skillet—all those golden browned bits (called fond) contain concentrated flavor. Add an additional tablespoon of olive oil to the same skillet and increase the heat to high. Once the oil is shimmering and smoking slightly, add the diced onion and jalapeño. Stir constantly for about 1 minute until the onion begins to soften and turns slightly translucent. Pour in the corn kernels and stir to combine with the onion mixture. Now here's the restaurant secret: don't stir constantly. Let the corn sit undisturbed on the hot surface for 2-3 minutes. You'll hear it popping slightly. Stir once, let it sit again for another 2 minutes. You want about 15-20% of the kernels to turn dark golden or slightly blackened—that char is what creates that restaurant flavor. Cover the skillet with a lid for 1-2 minutes to trap steam and soften the corn further. The corn should be tender but still slightly firm when you bite into it, and many kernels should have that beautiful dark color. Remove from heat.

Remove the creamy sauce from the refrigerator. Add approximately half of the sauce (about ⅓ cup) directly to the hot corn mixture in the skillet. Stir until every kernel is coated with the creamy, tangy sauce. The heat from the corn will slightly warm the sauce, creating the perfect temperature for serving.

Divide the cooked rice evenly among serving bowls, using about ⅔ cup per bowl. Create a small well or mound in the center of the rice. Place one chicken filet on top of the rice. Using a slotted spoon to leave excess sauce behind, top each bowl with a generous scoop of the creamy street corn mixture. Arrange the chopped avocado around the chicken, then sprinkle with the crumbly cotija cheese and fresh cilantro. Serve immediately with the remaining sauce drizzled over the top and a lime wedge on the side for squeezing.