In a large mixing bowl, combine ground beef, minced garlic, finely chopped onion, breadcrumbs, baking soda, chopped fresh herbs, olive oil, salt, and pepper. Mix thoroughly until well combined, then refrigerate for 2 hours.

Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper and form the chilled mixture into golf ball-sized meatballs, placing them on the sheet with space in between.

Bake the meatballs for 30 to 40 minutes until browned and cooked through, reaching an internal temperature of 160°F (70°C).

Cut potatoes into wedges, drizzle with olive oil, and season with salt, pepper, cumin, paprika, and oregano. Roast on a separate baking sheet for 40 to 60 minutes, turning halfway through.

In a medium bowl, mix together Greek yogurt, grated cucumber, minced garlic, lemon juice, dill or mint, and salt. Stir until combined and refrigerate while everything else cooks.

In serving bowls, layer fresh lettuce, salad ingredients (tomatoes, cucumbers, red onion, olives), roasted potatoes, and meatballs, finishing with a dollop of tzatziki.