Rinse Brussels sprouts. Trim off stem and then split in half, pulling off darker, loose leaves. Place brussels sprouts in a large microwave safe bowl with ¼ cup of water. Cover with a paper towel and microwave on high for 4 minutes.
Meanwhile, whisk together olive oil, mustard, salt, and pepper in a small bowl. Remove the brussels sprouts from the microwave and drain. Pour mustard sauce over sprouts and toss to thoroughly coat.
Heat gas or charcoal grill to medium high heat. Using tongs, place brussels sprouts on non-stick grill rack or grill wok, keeping the bowl nearby with the sauce reserved. Grill until browned and slightly charred on both sides, flipping half way through cooking, 4 to 5 minutes per side.
Remove brussels sprouts to the bowl with reserved mustard sauce. Toss gently to coat and serve immediately.
Recipe by The Taste Place at https://www.thetasteplace.com/everything-is-better-grilled-grilled-crispy-mustard-brussels-sprouts/