Snapedom

Good meta, Geri Chan, and I like everyone's comments. I, too, see Severus as being severely neglected, but I do think he would have learned to cook some very simple dishes in self-defense. However, I also think Smallpotato is right that he is too depressed, as the young adult we see in canon, to bother cooking much. It's a wonder he even remembers to eat!

How this adds up in my mind:
I am one of those who thinks the fish and chips wrapper on the riverbank was his. I think he'd like simple, traditional foods like this.
I don't see him fussing much (if at all) in the kitchen during canon, but, as I said, I think he would be able to cook some basic foods quite well. (In my personal canon, he learns from his maternal grandmother, both parents being dead by the time he's thirteen.) He loves bacon butties, and often makes them for breakfast, and he is, in his way, pertsnickety about tea. But, in general, in this period, he has neither the time nor the psychic energy to cook.
Post-canon, he actually learns to enjoy cooking, and the family cooks Sunday dinner together. I had a snippet of fic in mind to illustrate what I'd imagine this to be like, but never got to pound it out, as I had other deadlines and too much else going on.
His favorite foods:
Bacon, toast,porridge, fish and chips, tea, roast beef and Yorkshire pudding (when he can get it), colcannon and champ, and mashed potatoes generally, gravy. He's not much for fancy experimental stuff, in my mind. He does like food when someone puts it in front of him, but this is the sort of thing he is inclined to cook for himself.