There is some science behind why leftover brassicas like broccoli, cauliflower, and brussels sprouts have a somewhat less-than-desirable odor that develops when they sit in the fridge for a couple days after they have been cooked, which I am not fully versed in. But from a purely anecdotal perspective, I used to cut up 10-12 heads of cauliflower into teeny tiny florets every few days for this roasted cauliflower salad that was on the menu at this restaurant I worked at in Tennessee. The cauliflower would always be roasted on the same day that it was served, but sometimes I would try to get ahead and cut my cauliflower florets the day before I roasted them off. I was advised that if I was going to do this, I had to store the cut cauliflower in the walk-in fridge uncovered, because, as one of the more experienced cooks explained, if you leave them covered overnight after they have been cut, they smell like someone who has really bad gas. In any event, leftover brussels sprouts can be delicious, but they are really best when eaten right after they are roasted, as they can develop some strong odors when left in the fridge for a few days after they have been cooked.