Dice the onion, mince the garlic, cut zucchini into half moons about 1/4-inch thick, and halve the cherry tomatoes. Keep them in separate piles - they go in at different times.

Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the ground beef, breaking it up with a wooden spoon. Cook until deeply browned and crisp in spots, about 6-8 minutes. Transfer to a plate with a slotted spoon, leaving the fat behind.

Reduce heat to medium. Add the remaining tablespoon oil to the skillet. Add onion with a pinch of salt and cook until softened and just starting to color, 4-5 minutes. Stir in garlic, oregano, cumin, cinnamon, and red pepper flakes. Cook until fragrant, about 1 minute.

Add zucchini to the skillet. Cook, stirring occasionally, until it takes on some color and softens slightly at the edges, about 5 minutes. It should still have some bite - it will finish cooking with the tomatoes.

Stir in cherry tomatoes and return the beef to the skillet. Toss everything together and let cook until tomatoes soften and release their juices, about 3-4 minutes. You want some tomatoes to hold their shape while others collapse into a light sauce.

Remove from heat. Stir in lemon juice and taste for salt - the feta will add saltiness, so go light. Transfer to a serving dish, top with crumbled feta and fresh parsley. Serve warm with crusty bread or over rice.