Slice the zucchini into half-moons and the mushrooms into slices. Mince the garlic and set aside.
Heat a large skillet over high heat. Once hot, add the olive oil and heat until it shimmers.
Add the zucchini and mushrooms in a single layer. Let them cook undisturbed for 2-3 minutes to develop a char on one side.
Stir the vegetables and cook for another 2-3 minutes until they start to brown. Add garlic, salt, black pepper, and thyme (if using). Stir frequently, cooking for 2-3 more minutes until fragrant and tender.
Remove from heat. Optionally, squeeze lemon juice over the vegetables for brightness. Garnish with fresh parsley. Serve warm and enjoy!