Creating your Greek Meatball Bowl is simple when you follow these steps:

1. Preheat the Oven: Preheat your oven to 400°F (200°C).
2. Mix Meatball Ingredients: In a large bowl, combine the ground beef or lamb, breadcrumbs, Parmesan cheese, parsley, garlic, oregano, cumin, salt, pepper, red pepper flakes (if using), and the beaten egg. Mix well until fully combined.
3. Form Meatballs: Roll the mixture into golf ball-sized meatballs and place them on a baking sheet lined with parchment paper.
4. Bake Meatballs: Drizzle olive oil over the meatballs and bake in the preheated oven for 20-25 minutes, or until they are cooked through and golden brown.
5. Prepare the Base: While the meatballs are baking, cook your rice or quinoa according to package instructions.
6. Chop Vegetables: Dice the cucumber and tomato, and thinly slice the red onion.
7. Assemble Bowls: Once the meatballs are done, assemble your Greek Meatball Bowl. Start with a base of rice or quinoa, add several meatballs, and top with diced cucumber, tomato, and red onion.
8. Add Tzatziki: Drizzle tzatziki sauce over the top of the bowl.
9. Garnish and Serve: Serve with lemon wedges on the side for a fresh squeeze of juice.

These clear instructions will guide you in creating a delicious and fulfilling Greek Meatball Bowl that everyone will love.