Go find yourself some fatty bacon and suet at the grocery store.
Cook the bacon down to get as much grease as you can and add in some suet for more volume.
Get some old cans or other non-glass container and pour the grease in (after it’s not scolding hot) and either just let it sit, or put it in the fridge.
It will all harden back up (all sat fat!) and when you’re ready to use some, you can just get a few tablespoons or 1/4 cup or whatever and ‘melt’ it in a small pan then pour it on the dogs food.
You’re just rendering the fat and storing it for later.
Think of it like a tub of margerine. (literally a tub of lard).
One other thing I’ve done with my dogs when they get picky about dry nuggets or other food.
I sprinkle grated parmesan or romano cheese all over their food and mix it in. They loved it.
I’m sure it would work on a piece of meat, too. Hell, I’d make some cuts in it, sprinkle cheese and rub it in so it gets deep into the cuts so the dog doesn’t just lick the cheese off.
What about just buying a container of rendered pork fat? I’ve seen it at most grocery stores and Wal-Mart, it’s dirt cheap, and you just need to microwave a little glob of it for about 20 seconds so it’s soft but not hot, and it can be rolled with the other food using a large spoon or the like? The straight pork fat doesn’t have any nitrates/nitrites and would give you complete control over the salt content, as well.