Marinate chicken pieces with garlic paste, 2 tbsp chili sauce, red chili powder, cumin powder, dry oregano powder, lemon juice, and salt for 30 minutes. Heat oil in a pan and cook marinated chicken till fully done. Add a few drops of water if needed. Then add chopped capsicum, sliced onion, and 1 tbsp hot sauce. Cook for 2 minutes and remove from heat.
To assemble the Quesadilla: Heat some oil in a grill pan and place a sheet of roti/tortilla.
Spread 2 tbsp of chicken stuffing followed by tomato slices, a handful of grated mozzarella cheese, chopped coriander leaves, and red chili flakes.
Place the other sheet on top and cook till the bottom portion turns crisp.
Carefully flip over the whole quesadilla and cook on the other side as well till crispy and golden.
Remove and cut into four parts and serve hot.