Heat 2 tablespoons of water in a large soup pot. Add the onion and cook, stirring often, until the onion starts to soften.
Add the carrots, celery, and leeks. Continue cooking, stirring often, for about 5 minutes. Add the garlic and cook for another 30 seconds.
Add the tomato paste and stir. Cook for 30 seconds then add beans, diced tomatoes, stock, thyme, and pumpkin. Add salt and pepper to taste. Bring to a simmer and let cook for about 15-20 minutes, or until the pumpkin is tender.
Add the chopped kale and let cook for another 5-10 minutes. Taste and add more salt and pepper, if needed.