2 tablespoons butter
1 onion, diced
1/2 teaspoon ground cardamom
1/4 teaspoon ground turmeric
1/4 teaspoon ground ginger
1/4 teaspoon red pepper flakes
1/4 teaspoon ground cinnamon
1 pinch cayenne pepper
1 (14 ounce) can chicken broth
2 cups water
2 large sweet potatoes, peeled and diced
3 carrots, peeled and chopped
Salt and pepper to taste