In a very large fry pan, brown hamburger meat in three batches. Once the first batch is about half way browned, add 1/3 of the onion, 1/3 of the celery and 1/3 of the flour. Once the meat is browned, move the mixture to a big soup pot and repeat with two more batches.
Use an 8 quart soup pot. I have used a 6 quart, it works but a little tight on space.
Once all of the ingredients are in the big soup pot, add remainder of the ingredients and simmer for at least 30 minutes. If the mixture seems dry, or needs a little punch of flavor, I add a little bit of your favorite bottled bbq sauce.
Adjust seasonings to taste and serve on hamburger buns.
Important Note: if using 1/2 cup serving of sloppy joe mix per bun, this will make 50 Sloppy Joes. 1/2 cup makes an ample serving per bun with a little spillage off the sides of the bun. Like we all expect a sloppy joe to look.Using 1/3 cup serving per bun will yield 60 Sloppy Joes with a smaller about of meat per bun.If you'd like to Sloppy Joes using slider buns, this should yield about 80 - 100 Sloppy Joe Sliders.Hamburger Buns: Not all hamburger are created equal. There are some very large buns available for sale. Choose the smaller 3 1/2 inch buns for this recipe to accommodate the number of servings.