In a large bowl, combine ground beef, minced garlic, and finely chopped onions. Add breadcrumbs, baking soda, fresh herbs, olive oil, salt, and pepper. Mix well until fully combined, then cover the bowl with plastic wrap. Refrigerate the mixture for at least 2 hours to allow the flavors to meld.

Preheat your oven to 425°F (220°C). After chilling, roll the mixture into 1-inch meatballs and arrange them on a lined baking sheet. Bake for 30-40 minutes until golden brown and cooked through.

While meatballs bake, prepare the potatoes. Toss wedges with olive oil, salt, cumin, paprika, and oregano in a bowl. Spread on a baking sheet and roast for 40-60 minutes, flipping halfway through.

In a mixing bowl, combine Greek yogurt, grated cucumber, lemon juice, and chopped dill or mint. Stir thoroughly, season with salt, and chill in the refrigerator.

Start with a layer of lettuce leaves, then add diced tomatoes, cucumber slices, red onion, and olives. Layer in the roasted potatoes and meatballs. Top with tzatziki sauce and serve.