I'm hoping to create a custom food. I'm confident I can re-use a game mesh for "Japanese beef curry" and all my searching for help and tutorials leads me to AresFlare's custom foods tutorial as the clearest, best source for learnings. Unfortunately it starts with "You need to have your meshes ready before you start..."

I am a total N00b when it comes to meshes. Literally the extent of my mesh knowledge is, "Don't change the names, is bad!" so the simple phrase "have your mesh ready" has me dead in the water. Do I need to do an entire course on meshes and meshing before I attempt this? Or can someone kindly (ohplease??) direct me to the knowledge I need to learn before I can do the custom food learning?

I'm basically terrified, just staring at the "have your mesh ready" instruction as one giant Sphinx riddle, Pandora's Box, Narnia wardrobe, cliff edge of terror that's going to lead me down the rabbit hole into a vast pit of confusion.

If you are confident that you can re-use a game mesh for your own custom food, then use it. You will still need to extract it from the food you are cloning just for the sake of making your own new texture (Japanese beef curry) fit right on it. Which means you still need a 3D editor program to test this. Or, you go blindly...recoloring the maxis food texture with your own, praying that it will look acceptable in game.
I'm afraid you'll have to dab into meshing no matter what. Fear not, meshing is fun.

Thanks! I don't mind doing the work and learning a bit, I'm just so unfamiliar with anything at all mesh-y that I guess I don't even know what it is I need to know... you know?

Oh yes, I know. I totally understand.
If this can help you, I wrote a tutorial about texture mapping in Milkshape and post it on TSR ions ago.
I'll put it right here. This could help you mapping your new texture on the maxis food mesh.

That looks like it'll be a HUGE help in getting me started. Thanks so much! ^_^

You are welcome! there are other tutorials about this, for sure, as well. If you have any questions, I might be able to help.