Baking is different as it requires ingredients even without Simple Living challenge.
Here are my suggestions. First take a look at what is required.
- Buy the required harvestables in build mode with bb.showhiddenobjects cheat. Unfortunately, fishes you can get that way are bugged and unusable...
- Buy seed packets and open these. These do not actually contain seeds, but harvestables that can be used in cooking also.
- The Gallery has retail stores/rooms with the required ingredients.
- Get a fish bowl or an aquarium. You can buy fishes there.
- If you have Cottage Living, you can have grocery delivered.
- What expansions do you have? Some vendor stalls may sell some required ingredients. City Living and Cottage Living are great for harvestables, Cats & Dogs and Island Living are great for fishes.
Also raise your sim's Mischief level so they can buy voodoo dolls from the computer. 3 should do it.
Also raise a cowplant and have it eat sims (but not kill them) for emotion essences.