Pre-heat your oven to 400 degrees. 

Using a medium or large bowl, place the halved Brussels sprouts into the bowl, then add the olive oil, balsamic vinegar, salt, and pepper and toss them around to coat.

Dump the brussels onto a non-stick baking sheet and spread evenly. Place into oven and cook for 20-25 minutes. Check at 20 minutes to see if outsides are browned and crispy. Brussels should be fork tender and soft on the inside.

Using a medium or large bowl, place the halved Brussels sprouts into the bowl, then add the olive oil, balsamic vinegar, salt, and pepper and toss them around to coat.

Using an Air Fryer, spread the Brussels sprouts into the basket, then close and turn the air fryer to 400 degrees and set to 8 minutes. Open the air fryer and shake brussels around. Close the Air fryer and set for 6 more minutes at 400 degrees. Open basket and serve immediately.