Southwest Vegetarian Chili



1 medium onion, diced

1 15½ oz. can pinto beans, undrained

1 15½ oz. can navy beans, undrained

1 15½ oz. can kidney beans, undrained

2 14½ oz. cans diced tomatoes, undrained

1 can tomatoes & green chilies, undrained

1 15½ oz. can whole kernel corn, drained

1 pkg. low sodium beef stew mix

1 pkg. Ranch salad dressing mix

Sauté onions in a tablespoon of olive oil until onion is softened.  Transfer to stockpot or slow cooker and add remaining ingredients.  Cook on low for several hours if using slow cooker, or for 1 hour if using stockpot.  Serve with baked tortilla chips and sliced avocado.