Heat olive oil in a pan over medium-high heat. Add bell pepper and tomatoes. Sauté for 4–5 minutes until blistered.
Stir in garlic and cook for 1 more minute.
Add spinach and white parts of the green onion. Cook until wilted, about 2–3 minutes. Remove veggies to a plate.
Add ground beef, oregano, salt, and pepper. Brown until cooked through, then drain excess grease.
Return veggies to the pan. Stir in green onion tops. Warm everything together.
Top with crumbled feta and serve.
