Heat olive oil in a large skillet over medium heat until shimmering but not smoking. Add the finely chopped onions and sauté for about 2–3 minutes until they become soft and translucent.
Stir in minced garlic and cook for another 30 seconds until fragrant, ensuring not to burn it. Then add the ground beef into the pan, breaking it apart with a wooden spoon while cooking.
Season the beef with salt, black pepper, ground cumin, smoked paprika, dried oregano, and optional red pepper flakes for heat. Cook for about 5–7 minutes, stirring occasionally until fully browned.
Once the beef is cooked through, stir in the diced bell pepper and zucchini into the skillet. Cook everything together for about 5 minutes until the vegetables are slightly tender but still vibrant.
Next, fold in halved cherry tomatoes and sliced kalamata olives into the mixture; give everything a good stir to combine well. Allow it to cook for an additional 2 minutes so that tomatoes soften slightly but retain their shape.
Remove from heat and stir in freshly chopped parsley along with lemon juice for brightness. Serve topped with crumbled feta cheese and toasted pine nuts for added texture before enjoying this delightful dish!