Preheat the air fryer: Set it to 375°F (190°C). This helps the sugar caramelize quickly.

Prep the grapefruit: Wash and dry the fruit. Slice each grapefruit into 1/2-inch thick rounds. You can also halve them and slice into half-moons if that fits your basket better.

Remove seeds and loosen membranes: Use the tip of a knife to pop out any seeds. If you like, lightly score the fruit segments so flavors seep in and juices don’t pool.

Pat dry: Blot the cut surfaces with a paper towel. Less moisture means better caramelization.

Mix the topping: In a small bowl, combine brown sugar, cinnamon, and a pinch of salt. Stir in melted butter or coconut oil if using. You want a sandy paste that clings to the fruit.

Coat the slices: Lay the grapefruit rounds on a plate. Spoon or sprinkle the mixture evenly over the cut sides, pressing gently so it adheres.

Arrange in the air fryer: Place slices in a single layer in the basket, sugared side up. Do not overlap or they’ll steam instead of caramelize.

Air fry: Cook for 5–7 minutes, checking at the 4-minute mark. The sugar should melt and turn glossy with light browning at the edges. Cook 1–2 minutes more if you want deeper caramelization.

Rest briefly: Let the slices cool for 2–3 minutes. The topping will set slightly as it cools, creating a better texture.

Serve: Enjoy warm. Add yogurt, nuts, a drizzle of honey or maple syrup, and a few mint leaves if you like. Serve immediately for the best texture.