Begin by washing and slicing the zucchini into half-moons, ensuring uniform thickness for even cooking. Dice the mushrooms, roll the onion into ribbons, and mince the garlic.

Place a large skillet over medium heat and pour in olive oil, warming for about 1 minute until it shimmers.

Add the sliced onions to the skillet and sauté for about 3 minutes until they soften and become translucent.

Stir in the minced garlic and diced mushrooms, cooking for another 3-4 minutes until the mushrooms become tender.

Add the prepared zucchini, season with salt, pepper, and optional thyme, then sauté for an additional 3-5 minutes until tender yet slightly crisp.

Taste and adjust seasoning as necessary, ensuring all flavors are well balanced.

Transfer to a serving dish, garnish with freshly chopped parsley, and serve warm.