Heat 2 tablespoons olive oil in a large pot or Dutch oven. Add 1 large onion (chopped) and 2 carrots cut into thin slices and fry them gently for 3 minutes.
Add 3 cloves garlic (grated), 1 teaspoon ginger (grated), 2 teaspoons curry powder, 1 teaspoon turmeric powder, 1 teaspoon ground cumin, and ¼ teaspoon red pepper flakes and fry for one more minute, stirring often.
Add 5 cups vegetable broth, 1 can (15 ounces) crushed tomatoes, 1 cup dry lentils (rinsed), 1 pound potatoes (peeled and diced), 5 ounces kale (chopped), and season with 1 teaspoon salt and 2 twists black pepper.
Cover with a lid, bring to a boil on high heat, then crack the top open and let it simmer on medium heat for about 30 minutes or until the lentils are cooked. Stir occasionally.
Taste and adjust for salt and spices, then serve the soup in a bowl with a squeeze of lime or lemon on top and optionally some fresh cilantro or parsley.
