In a large bowl, gently combine the ground beef, grated onion, minced garlic, breadcrumbs, beaten egg, chopped parsley, cumin, paprika, oregano, red pepper flakes (if using), salt, and pepper. Mix until just combined, being careful not to overmix.

Cook a small amount of the mixture in a pan until browned. Taste and adjust the salt, pepper, or spices as needed.

Roll the mixture into 1-1.5 inch meatballs. Lightly wet your hands with cold water to prevent sticking.

Chill the meatballs for at least 30 minutes in the refrigerator to help them hold their shape.

Heat olive oil in a large skillet over medium-high heat. Add the meatballs to the skillet and brown on all sides, about 8-10 minutes, until cooked through.

Remove meatballs from the skillet and place them on a plate lined with paper towels to drain excess oil.

In a medium bowl, combine yogurt, minced garlic, olive oil, lemon juice, chopped dill, salt, and pepper. Whisk until smooth.

Taste the yogurt sauce and adjust seasoning as needed.

Chill the yogurt sauce for at least 30 minutes to meld the flavors.

Warm rice or pita bread according to package instructions.

Place a serving of rice or pita bread on each plate. Top with the cooked meatballs and spoon the yogurt sauce over the meatballs.

Garnish with fresh mint leaves, a drizzle of olive oil, and a sprinkle of Aleppo pepper flakes.

Serve immediately.