This recipe makes a substitute for a 1-ounce envelope of purchased dry onion soup mix. You can store 5-6 bags of onion soup mix in a wide mouth canning jar for 1 year. If you remove the oxygen from the canning jar, the onion soup mix will have a 10 year shelf life as long as the jar remains sealed. Once the seal is broken, the soup mix packages will have a one year shelf life. Dry Onion Soup Mix