Melt the butter in a Dutch oven over medium heat. Add the onions and caramelize for at least 20 minutes. Stir the onions to check on them about every 5 minutes. Adjust the heat if the onions are cooking too quickly or you notice and burn spots on the bottom of the pan. The onions will be very soft, will start to smell caramelized and you'll see spots of caramelization.
3 Tbsp. unsalted butter, 1 large yellow onion, diced
Add in the celery, carrots, mushrooms and seasonings and cook another 5 minutes, stirring occasionally. Then add the garlic and stir for another 30 seconds or so.
2 stalks celery, diced, 1 cup baby carrots, sliced into rounds, 1 cup baby bella mushrooms, sliced, 1 tsp. kosher salt, 1 tsp. Italian seasoning, 1/2 tsp. dried basil, 1/8 tsp. black pepper, 3 cloves garlic, minced
Then add in the broth, diced tomatoes, baby gold potatoes, sweet potato, corn, green beans, fresh herbs and Parmesan rind (optional). Stir to combine.
4 cups vegetable broth, 1, 28 oz. can diced tomatoes, with juices, 1 lb. baby gold potatoes, halved, 1 sweet potato, peeled and diced, 1 cup yellow corn (canned or frozen), 1 cup green beans, trimmed and cut into 1 inch pieces, 1/4 cup fresh parsley, chopped, 1 tsp. fresh thyme, chopped, 1 tsp. fresh rosemary, chopped, 2 bay leaves, 1 rind Parmesan (optional)
Bring this to a boil, then down to a simmer. Cover with the lid on until the potatoes are tender, ~20 minutes.
Lastly, stir in both beans and the lemon juice. Remove the rind and the bay leaves and discard. Taste the soup and adjust any seasonings, as desired. Also, if the soup is too thick, add more broth or water.
1, 15 oz. can white beans, drained and rinsed, 1, 15 oz. can kidney beans, drained and rinsed, 2 Tbsp. fresh lemon juice
Ladle into bowls and serve with crackers or bread. Enjoy!