Heat a drizzle of EVOO in a skillet. Add the chorizo and cook, crumbling with a wooden spoon, until browned. Drain off the fat.
Arrange the bread in a casserole dish. Top with the chorizo and then the roasted chiles.
Whisk together the milk, butter, hot sauce and eggs in a bowl and sprinkle with salt and pepper; pour over the chiles. Top with the cheese. Cover and refrigerate at least overnight and up to 2 days.
To serve, bring the strata to room temperature and preheat the oven to 325 degrees F. Bake the strata for 1 hour.
Meanwhile, whizz together the sour cream, avocado and lime juice in a food processor and season with salt and pepper.
Top the strata with tomatoes, cilantro and dollops of the avocado sour cream.
To roast the chile peppers, broil, turning occasionally with tongs and leaving the oven door ajar to allow steam to escape, until the skins are blackened all over. Transfer to a bowl, cover and let cool. Peel, seed and chop.