In a bowl, add the tuna, sardines, avocado, chickpeas, lemon juice and vegetable powder. Mash and mix very well with a fork until the mixture resembles a rough paste. Place the grated cheese on the left half side of each tortilla and top with the tuna mix. Fold the right side of the tortillas over on top. Place them on a skillet on high heat and cook each side for 1 minute until the cheese melts.