In a large soup pot, sauté onion in oil over medium heat until onions begin to turn translucent.(Or, if you prefer to avoid oil, use this method to saute without oil.)
Add garlic and sauté for one more minute or until garlic softens. (Don’t allow garlic to brown.)
Add squash, water, tomatoes, lima beans, and seasonings (except salt). Cover and bring to boil. Reduce heat and simmer for 40 minutes.
Stir corn and add salt to taste. Cook until heated through.