Core tomato and cut into 1/4" dice.

Drain, rinse, and cut roasted red pepper into 1/4" dice.

Slice olives into thin rounds.

Mince garlic.

Stem and mince oregano.

Trim zucchini ends, quarter lengthwise, and cut into 1/4" dice.

Halve and peel onion. Cut halves into 1/4" slices.

Coarsely chop a few onion slices to make about 1 Tbsp. chopped onion.

Stir together tomatoes, roasted red peppers, olives, 1 Tbsp. chopped onion (or to taste), garlic (to taste), oregano, 1 Tbsp. olive oil, 1/4 tsp. salt, and 1/4 tsp. pepper in a small mixing bowl.

Set aside for flavors to marry.

Place a large non-stick pan over medium-high heat.

Add 2 tsp. olive oil, zucchini, and sliced onion to hot pan.

Cook, stirring often, until browned and fork-tender, 3-5 minutes.

Season with 1/2 tsp. salt and 1/4 tsp. pepper.

Transfer to a plate and allow to cool 2 minutes.

Wipe pan clean and reserve.

Lay tortillas out on a clean counter.

Sprinkle mozzarella cheese on half of each tortilla and add zucchini-onion mixture.

Top with feta cheese (reserve a pinch for garnish).

Fold tortilla over filling and press gently so it holds in place.

Place pan used to cook vegetables over medium heat.

Add 1 tsp. olive oil to hot pan.

Working in batches, place two or three quesadillas in pan (there should be no overlap).

Cook until golden brown, 2-4 minutes per side.

Remove quesadillas from pan, add 1 tsp. olive oil to pan, and repeat with remaining quesadillas.

Halve quesadillas. Place on a plate, garnish with reserved feta cheese, and serve with olive salsa.