Cook the beef. Heat olive oil in a large skillet over medium heat. Add onion and cook for 3–4 minutes until softened. Add garlic and cook 30 seconds until fragrant.
Season and brown. Add ground beef to the skillet. Sprinkle with cumin, smoked paprika, coriander, oregano, salt, and pepper. Cook, breaking it up, until browned and cooked through.
Add zucchini. Stir in diced zucchini and cook for 2–3 minutes, just until tender but not mushy. Finish with lemon juice. Remove from heat.
Make the sauce. In a small bowl, whisk together Greek yogurt, garlic, lemon juice, olive oil, and salt until smooth.
Assemble the bowls. Divide rice and greens between bowls. Top with ground beef, tomatoes, cucumber, and feta.
Finish and serve. Drizzle generously with garlic yogurt sauce and serve immediately.
