Spicy Tomato and Lentil Soup

INGREDIENTS

• 1 onion, finely chopped
• 1 tablespoon olive oil
• 1 chile pepper, chopped
• 1 cup red lentils
• 1 (14.5 ounce) can peeled and diced tomatoes
• 1 cup water
• salt and pepper to taste
• 1/2 teaspoon ground cumin
• 1 teaspoon dried basil
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• 1/4 cup sour cream, for topping (optional)
• 2 sprigs fresh basil leaves for garnish (optional)