Heat 1 tablespoon of canola oil in a large skillet over medium heat. Stir in the diced sausage, poblano pepper, red pepper, red onion, and corn. Cook until soft, about 15 minutes.
Spoon 1/4 of the sausage mixture on one half of each tortilla; top each with 1/2 cup cheese. Fold over tortillas to make a half moon shapes. Repeat with remaining ingredients.
Heat the remaining 1 tablespoon of canola oil in large skillet over medium heat. Cook quesadillas until the cheese is melted and the tortilla is brown and crispy, about 5 minutes per side. Cut each quesadilla into 4 wedges, and top with sour cream and salsa, if desired.