Heat a saucepan over medium heat, add the oil and heat. Add shallots and sauté until tender, about 4 min. Add red peppers, oregano, red pepper flakes & chicken stock.
Bring to a simmer over medium-low heat, until sauce slightly thickened, about 15 minutes.
Let cool slightly and add to a blender and pulse until smooth. Return to the pot and whisk in the cream. Season to taste with salt and keep warm until ready to use.
Char poblano chilies over gas flame or in broiler until blackened on all sides. Enclose in paper bag for 10 min. Carefully peel off the charred skin, being careful to keep the stem intact.
Make a slit lengthwise down one side of each of the poblanos and use a small spoon to scoop out as many seeds as possible and discard.
Heat the oven to 375ºF (190ºC). Heat a sauté pan over medium heat add olive oil and heat. Add the butter and melt then add the onion and sauté until tender, about 6 min.
Add the corn and cook until the corn is tender, about an additional 4 minutes.
Add the shrimp and fish, cooking until the shrimp are firm and pink and the fish is flakey and just cooked through, about 4 minutes.
Move to a large mixing bowl if needed. Stir in the rice, cilantro and ½ cup of the red pepper sauce until combined and set aside.
Spoon the filling into the poblanos until they are plump. Spread 1 cup of the red pepper sauce in the bottom of a baking dish and arrange the filled poblanos on top.
Top with the cheese. Cover with aluminum foil and bake until the cheese has melted, about 15 to 20 minutes.
Spoon the remaining red pepper sauce onto each plate and top each with a chile. Sprinkle with cotija cheese and serve with lime.