In a large skillet over medium-high heat, combine the ground lamb and ground beef.
Cook the meat, breaking it into small crumbles, until browned and cooked through (approximately 8-10 minutes).
Drain excess fat from the skillet.
Stir in the minced garlic, oregano, cumin, onion powder, salt, and pepper; cook for an additional 2 minutes until fragrant.
In four meal prep containers, divide the cooked rice evenly.
Top the rice with the seasoned meat mixture.
Divide the cucumbers, tomatoes, red onions, olives, and feta cheese among the bowls.
Drizzle with tzatziki sauce before serving or store sauce in separate small containers for later use.