Scoop out the Avocado (1) into a bowl. Add the Lemon Juice (2 tablespoon), and season with Salt (to taste). Using a fork, mash everything together.
Divide the avocado mixture between four of the Tortilla (8). Using the back of the spoon, spread out the avocado over the surface. Also, divide the Canned Tuna (400 gram) among the four tortillas.Top with Fresh Baby Spinach (50 gram),and Cheddar Cheese (1 cup).
Place the remaining tortillas on top to sandwich them together.
Use a regular frying pan with some oil in it, and separately cook each tortilla sandwich for 2 minutes each side.
Use a Pizza cutter or a knife to cut the Quesadilla into wedges. Serve and enjoy!