Preheat oven to 400º. Line a large, rimmed baking sheet with parchment paper. Set aside.
Combine oil and onion in a small skillet over medium heat. Cook until mostly translucent, about 3 minutes. Add 1 clove minced garlic, cumin, salt, pepper, and red pepper flakes. Stir, and cook until very fragrant, about 2 minutes. Transfer onion mixture to a small bowl, and set aside to cool for 5 minutes.
Combine 1 1/2 tablespoons fresh dill (or 1 teaspoon dried dill), 1 tablespoon mint, breadcrumbs, and cooled onion mixture in a medium bowl. Add ground meat and egg white. Use your hands to mix everything thoroughly, being careful not to squish or compact the meat too much. Roll meat mixture into 1-inch meatballs (you should end up with about 20 total). As you roll them, place meatballs on the prepared baking sheet. Bake meatballs until tops are golden brown and insides are cooked through, 15 to 20 minutes, depending on the kind of meat you choose.
While meatballs bake, cook orzo according to package directions. Heat the remaining oil in a small saucepan over medium-low heat. Add remaining garlic, and stir until fragrant and just turning golden. Add crushed tomatoes or marinara, and remaining herbs. Stir, and taste. Add salt and pepper to taste. Cook until heated through.
To serve, divide orzo among 4 serving bowls. Spoon 1/2 cup sauce over each serving, and top with 4 or 5 meatballs. Top with crumbled feta, or pass it at the table so everyone can add the amount they prefer.