Heat oil to 400 in a large, high walled pot. Fry brussel sprouts for 8-10 minutes till crunchy. (Caution, vegetables have a large amount of water and will cause oil to bubble up). Cook ½ cup of brussels at a time. Remove and drain on sheet pan layered with paper towel. Season with salt.
Toss in a bowl with garlic, and char siu sauce. Plate and garnish with chili Crisp.
For Air Fryer, Coat brussel sprouts with 6 tbs of oil and season with salt. Air fry at 375 for 9 to 12 minutes and shake the basket occasionally to fry evenly. Toss fried sprouts with char siu, plate and garnish with chili oil.