Prerequisites: Max out Kipps' level 1 friendship
Reward: Grilled Fish Recipe (I think)
Unlocks: Kipps level 2 friendship, The Cat's Favourite
Before you can trigger this quest you first need to max out the first level of your friendship with Kipps, the black cat that lives on the fringes of Moonbury Town. Kipps travels all over the place in Moonbury on any given day, and aside from using your dog you'll likely come across Kipps at random. The only reliable spot to find Kipps is at Zeke's Tent, to the southwest of Moonbury and beside the Bulk and Build, and even then you'll only spot Kipps there in the morning and the evening.
Head to Zeke's Tent on Monday to Friday, 9:00 to 15:00 once you're sufficiently friendly with Kipps. You'll catch Zeke and Kipps outside, and Kipps is mad because she's not receiving her 'special treat'. Zeke asks you to visit Ottmar on his behalf. You'll typically find Ottar hanging out at the Primerose Sail in the northwest of Moonbury Town, either in the ship or out on the docks.
Ottmar is happy to get Kipps the grilled fish she wants, but he needs five White Meat to make the dish. You can get White Meat by fishing. Buy a handful of Worms from the Primerose Sail and fish over at the Park Fishing Spot. It won't take long to snag five pieces of White Meat for Ottmar. Take the meat back to him and he'll cook up a Special Grilled Fish.
Take the Special Grilled Fish to Zeke. He wanders all over Moonbury on any given day, so you'll likely need to have your dog hunt him down for you. Handing over the Special Grilled Fish will endear you to Kipps, raising your relationship with her to the next level, and end the quest. You'll also unlock the path to Kipps' next quest, The Cat's Favourite.
(When I completed this quest the game told me that I'd earned a Recipe, which I assume was for Grilled Fish. Nothing got unlocked under the Food menu, though, so... perhaps this is a bug that needs to be addressed.)