Marinate the chicken the day before and serve it with the pita bread and salad that only takes a few minutes to put together.
In a large bowl, toss chicken tenderloins with garlic, cumin, 2 tablespoons lemon juice, and 2 tablespoons extra-virgin olive oil; season with coarse salt and ground pepper. Cover and refrigerate for later use.
Preheat oven or toaster oven to 350 degrees. Wrap pitas in foil. In a medium bowl, combine cucumber, yogurt, and lemon juice; season with salt and pepper.
In a large skillet, heat 1 tablespoon oil over medium-high. Add onion, season with salt and pepper, and cook until softened, about 5 minutes. In batches, add chicken and cook until browned, 2 to 4 minutes per side (adding 1 tablespoon oil for second batch).
Meanwhile, bake pitas until warm, about 5 minutes. Stir mint into cucumber salad. Serve chicken with pitas and salad.