If you have a large family or would just like to keep a larger quantity on hand at all times, like me, I thought I'd just post my bulk recipe here. It blends up quite quickly in a food processor and stores indefinitely in an airtight container. I am sure it would get stale or lose flavor at some point, but we always use ours up within a year and have had no issues storing it that long.
I am posting these amounts because I don't know what size food processor everyone has or just how much they want to make, but I purchase my ingredients in bulk and I typically make the below recipe x4 at a time in my 7 cup food processor.
1 cup dry minced onion
1/2 cup GF DF beef bouillon powder (= 24 cubes)
3 tsp. onion powder
1/2 tsp. celery seed
1/2 tsp. sugar OR 1/4 tsp. garlic powder (depending on your personal preferences. You could omit both. See note below)
Place all ingredients in food processor and blend until combined (if using cubes of bouillon make sure they are all blended so no chunks remain, otherwise, process until dry minced onion is desired size and other ingredients are combined). Store in airtight container. Use 1/4 cup of this mix (to taste, you may find this has a slightly stronger or milder taste than the packaged dry onion soup mix depending on the quality of the ingredients you used in comparison) to replace one envelope/packet of Lipton's dry onion soup mix in recipes.
Note: The "traditional recipe calls for sugar, but we really enjoy garlic and don't miss the sugar at all so we changed it to suit our tastes. You can do the same. Some recipes call for a touch of black pepper. You may prefer to scale back the celery seed. Don't make the mistake I did once and substitute celery salt for celery seed. I thought it wouldn't make that much of a difference since it was only 1/2 tsp, but it was far too salty for our tastes that time and we had to scale back and use less of the soup mix in recipes.