Hi, @667TheNeighbourOfTheBeast.
I use canned or frozen chicken or beef stock cubes and water, then thicken it with corn flour, maybe add some herbs, seasoning and mustard, and/or a dash of wine or mushroom ketchup.
You could buy something like a Potts beef stock in a can and freeze it in an ice cube tray?
Potts beef stock Ingredients
Water, Beef Stock Base (7%) (Beef Stock, Water, Yeast Extract, Salt, Lemon Juice Concentrate, Beef Fat), Salt, Sugar, Lactic Acid
Low FODMAP was a pain at first, but it helped a lot. I think you get used to it after a while, honestly 