When Hermione cooks dinner, the food may not be good, but it will most certainly be healthy: lean meat if there's any, vegetables that don't grown in Britain, and if they're allowed dessert, it's fruit. She's always vaguely surprised when following the recipe leads her down a wrong turn, and they're left with wilted broccolli or scorched rice or chicken that, after precisely five minutes per side, is still pink. She is fond of asparagus but not the piss experiments that always follow.
When Harry cooks dinner, the food may not be fancy, but it will definitely be there: potatoes, bacon, just about anything with cheese. He favors things that come from boxes and bags, and has perfected a spell for defrosting and cooking a pizza with one careful flick of the wrist. He has the uncanny ability to fry just about anything, but he doesn't enjoy it, and the best that can be said about his culinary skill is that he leaves the kitchen cleaner than he found it.
This is why they try to leave dinner to Ron.
He puts on the wireless and twists the knob until the music coming out sounds like a jazz combo and a bagpiper in a centrifuge. He shuts the door. The bag of frozen peas on the shelf is reserved for the next black eye or sprained knee, and the tofu is acknowledged with contempt. Pots and pans appear, the great cast-iron behemoths that Hermione bought because they were recommended in some magazine, and the knives begin chopping. Some things he will only do by hand, like trimming gristle from the roast or slicing onions until his eyes spill over. A whole stick of butter goes in for the sauce, and much too much salt on the roast, not to mention the generous measure of red wine in the bottom of the pan—his mother's trick, though she rarely admits to it. Another measure of wine in the cook, and then he browns the roux (because conjured sauces never taste quite right) and starts the potatoes and the beans in their pots. He can tell by scent which of the spices are still good, and by taste how much need to go where. He's quite fond of garlic and, unfortunately, cayenne pepper. Things begin to simmer and boil, aromas begin to rise out of the pots, and while he waits he whips a bowl of sweetened cream until his arm begins to ache.
Events proceed apace now. He Summons out serving dishes and starts to put out the vegtables. The potatoes go over a bit, so he mashes them up, and then the roast comes out and gets transferred to a platter with difficulty. Hermione won't want the sauce so he serves it on the side, and almost as an afterthough he puts out wine glasses and the rest of the red. The door opens while he's wiping his hands on a frayed and dripping towel.
"Well?" he asks with a grin. "How's it look?"
Hermione looks at the sauce in its tureen, and the fatty drippings oozing from the roast, and the mashed potatoes that are probably swimming with butter and cream. Harry looks at the flour spilled across the counter and the floor, the teetering pile of dishes in the sink and the bits of things that didn't make it into the bin. Ron's sleeves are rolled up and he's got juice down his front, and he's sucking on a sliced fingertip with a raised-eyebrows grin.
They beam at him. "It looks amazing."
"I'll never understand it," Hermione comments as they tuck in. "You can do this, but you nearly failed Potions."
"I never cared about Potions," he says, and shrugs.
Harry comes up for breath and asks almost hopefully. "Did you make anything for afters?"
"Whipped cream."
"Anything to go with it?"
"I think we can find something."
And they did.