I use leftover sauce from cans of Pork and Beans or Ranch Style Beans. It’s almost free. Keep in Freezer in container.
When you have enough for a batch, soak beans overnight, drain water, rinse, boil with a pinch of baking soda, drain this water, then simmer with the leftover sauce until tender. Better yet, cook in a crockpot all day on low. You can also add these to any soup once they are cooked.
An easy way to make leftover stew is to accumulate leftovers “too small to save” in another freezer container until full. Add beans to these for Surprise soup. I also use them in a simple soup using water, canned spinach (drained), macaroni, and stewed tomatoes, either canned or fresh.
Flavoring is easy, I always add a bay leaf or two, salt, pepper.
If all else fails, puree them and add to make “faux” cream soups.