Easy Chicken Gyros & Tzatziki Sauce

chicken breasts, pounded to ½ inch thickness

mediterranean seasoning (you can substitute Italian seasoning in a pinch)

red pepper, thinly sliced

red onion, thinly sliced

pitas (this is a Greek-style flatbread you can find at almost any grocery store near the bread and tortillas or in the bakery)

optional: lettuce, feta cheese crumbles

English cucumber, peeled and diced

cold plain Greek yogurt

minced garlic

chopped dill, fresh or frozen (may sub 2 tablespoons dried dill)

freshly squeezed lemon juice (juice of ½ medium lemon)

salt, or to taste

black pepper