Preheat the air fryer to 390–400°F (200–205°C) for 3 to 5 minutes.
A hot basket helps the veggies crisp.
Cut the florets. Trim broccoli and cauliflower into bite-size florets, about 1 to 1.5 inches wide. Keep them similar in size for even cooking.
Rinse and dry well.
Pat the florets dry with a clean towel. Excess moisture makes them steam instead of roast.
Season. In a large bowl, toss florets with olive oil, garlic powder, onion powder, smoked paprika, salt, and pepper.
Add lemon zest for brightness.
Load the basket. Spread florets in a single layer. If your air fryer is small, cook in two batches so the basket isn’t crowded.
Air fry for 10 to 12 minutes, shaking the basket halfway.
You’re aiming for tender stems and lightly crisped edges. For extra color, add 1 to 2 minutes.
Finish. Transfer to a bowl and squeeze fresh lemon juice over the top.
Taste and adjust salt, then add any optional toppings like Parmesan or red pepper flakes.
Serve hot as a side or toss into bowls, salads, or pastas.