Prep the vegetables. Wash and dry everything well. Moisture is the enemy of crispness. Cut broccoli and cauliflower into small florets, carrots into 1/4-inch coins, bell pepper and zucchini into bite-size chunks, and onion into 1-inch wedges.
Keep sizes consistent. Aim for similar-sized pieces so they cook at the same rate.
If using dense veggies like carrots or sweet potatoes, cut them a touch smaller than soft veggies like zucchini.
Toss with oil and seasoning. In a large bowl, combine the vegetables with oil, salt, pepper, garlic powder, paprika, and thyme. Use your hands or a spatula to coat evenly. You want a light, even sheen—no puddles of oil.
Preheat the air fryer. Set to 390–400°F (200–205°C) for 3–5 minutes.
A hot basket helps the vegetables start browning immediately.
Arrange in the basket. Spread the veggies in a single layer with a little space between pieces. Do not overcrowd. If needed, cook in batches for the best results.
Air fry and shake. Cook for 10–14 minutes total, shaking the basket or stirring every 5 minutes. Start checking at the 8-minute mark.
You’re looking for caramelized edges and tender centers.
Finish and taste. Transfer to a bowl and toss with lemon juice or vinegar. Add parsley, Parmesan, or red pepper flakes if you like. Taste and adjust salt and pepper.
Serve hot. These are best right away.
Pair with grilled chicken, salmon, pasta, grain bowls, or tuck into wraps.