Where the flavor of brussel sprouts comes from

Cruciferous vegetables such as brussel sprouts are made up of sulfur-containing compounds called glucosinolates that give them their distinct smell and bitter flavor when cooked. The smell and flavor are strongest when overboiled. Oven roasting brussel sprouts instead can result in a nutty, sweet flavor.

Source: Science of Flavor: Cruciferous Vegetables. Harvard T.H. Chan School of Public Health. Accessed December 12, 2023. https://www.hsph.harvard.edu/nutritionsource/2016/11/21/science-of-flavor-cruciferous-vegetables-brussels-sprouts/