In a slow cooker, add the chopped onion, frozen vegetables, canned tomatoes, potatoes, bay leaf, Italian seasoning, minced garlic, salt, and pepper.
Pour the vegetable stock over the ingredients in the slow cooker.
Set your slow cooker to Low setting and cover with the lid. Cook for 4-6 hours for a thorough simmer or on high setting for 2-3 hours for a quicker soup.
About 30 minutes before serving, check the potatoes for tenderness. They should be soft when pierced with a fork.
Adjust seasoning for salt and pepper and serve.
Notes
Consider adding cooked beans or pasta during the last 30 minutes of cooking. If you prefer a thicker soup, you can mix 1-2 tablespoons of cornstarch with a small amount of cold water and stir it into the slow cooker during the last hour of cooking. Stir well to avoid lumps.Garnish with fresh herbs like parsley or a sprinkle of grated Parmesan cheese before serving for extra flavor.