Trim the stem ends of the Brussels sprouts and remove any discolored outer leaves. Cut them in half lengthwise for even cooking.
Heat the avocado oil in a large skillet over medium-high heat. Add the Brussels sprouts, cut side down, in a single layer. Sprinkle with salt and black pepper. Reduce heat to medium and let them cook without stirring for about 6-8 minutes until the flat side starts to caramelize and the sprouts are becoming tender..
Stir and pour the balsamic vinegar into the pan alongside the Brussels sprouts and cook for another 2-3 minutes, allowing the vinegar to reduce.
Stir to coat the sprouts with the reduced vinegar and serve.
Notes
LeftoversStore leftover Brussels sprouts in an airtight container in the refrigerator for up to 4 days. Reheat in the microwave, on the stovetop (over medium heat with a little extra oil) or in the oven (350 F for 10 minutes).