In a skillet over medium-high heat, add the olive oil, bell pepper, jalapeno and onions and cook until starting to soften, 3 to 4 minutes. Add the ground beef and cook until totally browned, about 8 minutes. Add the chili powder, cumin, salt, black pepper and crushed red pepper and stir to combine.
Pile the mixture into individual romaine lettuce leaves and top each with 2 tablespoons pepper jack, 1 tablespoon chopped tomatoes, one-eight of the red onion, 2 slices of avocado, one-eighth of the corn, a dollop of sour cream, 1 tablespoon cilantro and 1 lime wedge.