1. Heat olive oil in a large skillet over medium-high heat.
2. Sauté diced red bell pepper and cherry tomatoes for 4 to 5 minutes until tomatoes blister and become saucy.
3. Add minced garlic and cook for another minute.
4. Stir in baby spinach and the white parts of the green onions; cook until spinach wilts, about 2 to 3 minutes.
5. Remove vegetables to a plate.
6. Add ground beef to the skillet; season with oregano, salt, and pepper.
7. Cook, breaking the meat apart evenly, until browned.
8. Drain excess grease if necessary.
9. Return cooked vegetables to the skillet and add the green onion tops.
10. Stir everything together and heat through.
11. Finish with crumbled feta cheese, fresh parsley, and a squeeze of lemon juice, if desired.
12. Serve over rice, quinoa, or in butter lettuce wraps.
13. Optionally add extra vegetables or a fried egg for variety.