Warm 3 tablespoons of the olive oil in a large Dutch oven or soup pot over medium heat. Once the oil is shimmering, add the chopped onion, carrot, celery, seasonal vegetables and ½ teaspoon of the salt. Cook, stirring often, until the onion has softened and is turning translucent, about 6 to 8 minutes. Add the garlic, curry powder and thyme. Cook until fragrant while stirring frequently, about 1 minute. Pour in the diced tomatoes with their juices and cook for a few more minutes, stirring often. Pour in the broth and water. Add ½ teaspoon more salt, 2 bay leaves and the red pepper flakes. Season generously with freshly ground black pepper. Raise the heat and bring the mixture to a boil, then partially cover the pot and reduce heat to maintain a gentle simmer. Cook for 25 minutes, then remove the lid and add the chopped greens. Continue simmering for 5 minutes or more, until the greens have softened to your liking. Remove the pot from heat and remove the bay leaves. Stir in the lemon juice and remaining 1 tablespoon of olive oil. Taste and season with more salt, pepper and/or red pepper flakes. (You might need up to ½ teaspoon more salt, depending on your vegetable broth and your personal preferences.) Divide into bowls and enjoy.