Soften tortillas by microwaving briefly if they are stale.
For burrito size tortillas, get one small oven-proof bowl for each shell and a large baking sheet. Set the bowl(s) upside down on the baking shet and spritz lightly with oil. Press the tortillas around the bowls, pressing and folding them so they keep their shape. Spray outside lightly with oil.
For taco-size tortillas, turn a muffin tin upside down. Spritz both sides of each tortilla lightly with oil and tuck into the space between muffin cups.
Bake for 8 minutes. For large tortillas, after 8 minutes, carefully flip the tortillas off the bowls (lift away from you to avoid steam burning your hand) and return to the oven for another 2-4 minutes to cook completely. Small tortillas will be cooked after 8 minutes.
Spread beans in the bottom, then top with meat or veggies of your choice, then salad ingredients.