Rinse Brussels sprouts under cold water. Trim the tough stem ends with a sharp knife, then cut each sprout in half lengthwise. Save any loose outer leaves—they will crisp beautifully. Transfer halved sprouts to paper towels and pat completely dry. Any surface moisture will prevent crisping.

Transfer dried sprouts to a large mixing bowl. Drizzle with avocado oil and toss with your hands until every surface is lightly coated. Add kosher salt and black pepper. Toss again. Do NOT add garlic yet—it will burn at high heat.

Set your air fryer to 400°F (204°C) and preheat for 3-4 minutes. A hot basket prevents sticking and kickstarts caramelization immediately when the sprouts make contact.

Once preheated, arrange Brussels sprouts in a single layer in the air fryer basket, cut-side down. This positioning maximizes contact with the hot surface for deeper caramelization. Leave space between each sprout half—crowding causes steaming instead of crisping. Cook in batches if needed.

Close the basket and cook for 10 minutes without opening. Let the Maillard reaction and caramelization work undisturbed. You'll smell sweet, nutty aromas around the 6-minute mark—that's the sugars breaking down and browning.

At 10 minutes, open the basket and shake firmly or use tongs to flip the sprouts. The cut surfaces should be golden brown with crispy, charred edges. If not quite there, cook another 2 minutes before proceeding.

Sprinkle minced garlic evenly over the partially roasted sprouts. Toss gently to distribute. Close the basket and cook for 3-4 more minutes. This timing allows garlic to toast and become fragrant without burning. Adding it earlier causes bitter, charred garlic.

Check for doneness—outer leaves should be deeply caramelized and crispy like chips. Cores should be tender when pierced with a fork. Transfer to a serving bowl. While hot, drizzle with balsamic glaze, add red pepper flakes, or sprinkle Parmesan. Toss once more and serve immediately.