Pureeing this lima-bean soup makes it creamy; tiny pasta shapes add texture, and roasted red bell peppers give the soup an appealing fall color.
Heat broiler. Place peppers, skin sides up, on a baking sheet. Broil 4 inches from heat until charred, 18 to 20 minutes. Let cool slightly; using a paper towel, rub off blackened skins. Coarsely chop peppers; set aside.
Heat oil in a large saucepan over medium heat. Cook onion and carrots until beginning to soften, about 5 minutes. Add garlic, and cook until fragrant, about 1 minute.
Add broth, thyme, lima beans, and 2 cups water. Bring to boil; reduce heat to medium-low. Cover; simmer 15 minutes. Stir in basil and lemon juice.
Working in batches (do not fill container more than halfway), puree soup in a blender or food processor until smooth. Return soup to pan; bring to a boil, and add pasta and reserved peppers. Season with salt and pepper. Serve hot.