Homemade Hamburger Peppers And Onion Gyros

Ingredients:

1 lb ground beef (80/20 or 85/15)
1 medium onion, thinly sliced
1 green bell pepper, thinly sliced
1 red bell pepper, thinly sliced
2 cloves garlic, minced
1 tablespoon olive oil
1 teaspoon dried oregano
1/2 teaspoon ground cumin
1/2 teaspoon paprika
Salt and pepper, to taste
4 gyro-style flatbreads or pita bread
Tzatziki sauce (store-bought or homemade)
Optional toppings: sliced tomatoes, sliced cucumbers, crumbled feta cheese, lettuce
Homemade Tzatziki Sauce (optional):
1 cup Greek yogurt
1/2 English cucumber, grated and squeezed to remove excess moisture
1 clove garlic, minced
1 tablespoon fresh dill, chopped
1 tablespoon fresh lemon juice
Salt and pepper, to taste