1Cut large mushrooms in halves or quarters. Slice zucchini into thick rounds, bell peppers into large pieces, carrot into rounds, and celery into cubes. Cut red onions into quarters. Leave cherry tomatoes and garlic cloves whole.
2In a large bowl, mix all vegetables. Drizzle with olive oil and season with salt, pepper, fresh thyme, and optionally other spices. Toss well to coat evenly.
3Air fryer method: Transfer seasoned vegetables to the air fryer basket. Cook at 200°C (400°F) for 30 minutes, shaking or stirring twice (every 10 minutes) for even browning.
4Oven method: Preheat oven to 200°C (400°F). Spread vegetables in a single layer on a baking sheet. Roast for 35–40 minutes until lightly caramelized and tender.
5Serve immediately, hot. They are a perfect side for meat, fish, or tofu, or can be a main dish with a fresh salad and crusty bread.