Step 1

Heat an air fryer to 375ºF. Meanwhile, trim 1 pound Brussels sprouts and halve any that are larger than an inch wide. Transfer to a medium bowl, add 1 tablespoon olive oil and 1/2 teaspoon kosher salt, and toss to combine.

Step 2

Add the Brussels sprouts to the air fryer and shake into a single layer. Air fry, stopping to shake the basket (or rotate the pans in larger air fryers) about halfway through, for 15 minutes total. Meanwhile, prepare the shallot butter.

Step 3

Finely chop 1 medium shallot. Place 2 tablespoons unsalted butter in a medium microwave-safe bowl and melt in the microwave. (Alternatively, melt in a medium saucepan over low heat, then remove from the heat.) Add the shallots and 1 teaspoon red wine vinegar and stir to combine.

Step 4

When the Brussels sprouts are ready, transfer into the bowl or saucepan with the shallot butter and toss to combine. Serve immediately.