Preheat the air fryer: Set it to 390°F (200°C) for 3–5 minutes. A hot basket helps the carrots brown nicely.
Prep the carrots: Peel and cut into even pieces.
Aim for 1/2-inch thick so they cook through without burning.
Toss with oil and seasoning: In a bowl, combine carrots, olive oil, salt, pepper, and the optional coriander or cinnamon. Coat evenly.
Air fry the carrots: Add carrots to the basket in a mostly single layer. Cook for 8–10 minutes, shaking halfway.
They should be tender with browned edges.
Make the sticky glaze: While the carrots cook, melt the butter in a small pan (or microwave). Stir in honey (or maple) and vinegar or lemon juice until glossy and combined.
Glaze and finish: Transfer hot carrots back to the bowl and pour over the warm glaze. Toss to coat.
Stir in orange zest if using.
Add hazelnuts: Fold in the chopped toasted hazelnuts. Taste and adjust salt and acidity. A pinch more salt or a few drops of vinegar can wake up the flavors.
Serve: Finish with flaky sea salt and herbs.
Serve warm as a side, or pile on grains with feta for a simple meal.