Htydjtk

I would like to identify a short story I read in maybe 50’s or 60’s about a space freighter cook driven mad by a crew member putting ketchup on his increasingly elaborate and tasty meals created from recycled waste. On the last voyage he serves up his antagonist!

This is "Gourmet" (1962) by Allen Kim Lang, first published in Galaxy Magazine; the full text is legally available at Project Gutenberg.

This was the endless problem of all spaceship cooks: He had to feed the men tomorrow on what they had eaten today!

The story revolves around a spaceship's crew, focusing on its cook, Robert Bailey, nicknamed "Belly-Robert" by Captain Winkelmann. The story is narrated by the ship's doctor.

Throughout the story, Bailey does his best to provide the crew with "groundlike" food, using various chef techniques to make them forget the fact they're eating recycled waste. Even though it's not perfect, most of the crew members appreciate his efforts. The captain isn't even remotely pleased, however, and the meals are never to his taste. He's being rough and borderline rude to Bailey, on a daily basis, up until he commits the unforgivable, by pouring Ketchup on the ersatz steak the Cook presented him.

"But it still needs something ... something,"
Winkelmann went on, slicing off another portion of the tasty
Chlorella. "Aha! I have it!"

"Yes, Sir?" Bailey asked.

"This, Belly-Robber!" Winkelmann reached beneath the mess-table and
ripped open his cardboard carton. He brought out a bottle and
unscrewed the cap. "Ketchup," he said, splattering the red juice over
Bailey's masterpiece. "The scarlet burial-shroud for the failures of
Cooks." Lifting a hunk of the "steak," streaming ketchup, to his
mouth, Winkelmann chewed. "Just the thing," he smiled.

"Damn you!" Bailey shouted.

Winkelmann's smile flicked off, and his blue eyes pierced the Cook.

"... Sir," Bailey added.

"That's better," Winkelmann said, and took another bite. He said
meditatively, "Used with caution, and only by myself, I believe I have
sufficient ketchup here to see me through to Mars. Please keep a
bottle on the table for all my future meals, Belly-Robber."

"But, Sir...." Bailey began.

"You must realize, Belly-Robber, that a dyspeptic Captain is a threat
to the welfare of his ship. Were I to continue eating your
surrealistic slops for another hundred days, without the small
consolation of this sauce I had the foresight to bring with me, I'd
likely be in no condition to jet us safely down to the Piano West pad.
Do you understand, Belly-Robber?" he demanded.

"I understand that you're an ungrateful, impossible, square-headed,
slave-driving...."

"Watch your noun," Winkelmann cautioned the Cook. "Your adjectives are
insubordinate; your noun might prove mutinous."

The story ends with the crew members being lured to the mess by the exquisite odor of grilled meat, Bailey having seemingly reached his goal of recreating enjoyable food from offal. While savoring the meal, the Doc comments on the Captain being a hard man, but eventually pushing his Cook to achieve his greatest creation. Cailey asks the Doc whether he came to like the Captain.

Bailey stood up. "Do you like Captain Winkelmann, Doctor?" he asked.

I thought about his question a moment. Winkelmann was good at his job.
He persuaded his men by foul means, true; but it was all for the good
of the ship and his crew. "Do I like Captain Winkelmann?" I asked,
spearing another piece of my artificial steak. "Bailey, I'm afraid
I'll have to admit that I do."

Bailey smiled and lifted a second steak from the warming-pan onto my
plate. "Then have another piece," he said.

Found with the Google query "science fiction" "ketchup" "tasty" "freighter" site:archive.org. I had a bit of luck, since "Gourmet" doesn't contain the word "freighter", but another story collected along it on the Internet Archive had it.