Seed tomatoes and cut into 1/4-inch dice. Quarter avocado, removing pit, and peel. Cut avocado into 1/4-inch dice. In a small bowl stir together tomatoes, avocado, onion, lemon juice, and hot sauce and season with salt and pepper. In another small bowl stir together sour cream, coriander, and salt and pepper to taste.
In a lightly oiled non-stick skillet, lay a tortilla. Sprinkle with Monterey Jack cheese. Place another tortilla on top of cheese. Heat until cheese melts. Make 3 more quesadillas.
Cut quesadillas into 4 wedges. Top with avocado and sour cream.
Recipe courtesy of Gourmet Magazine