Indian Spiced Carrot Soup

Ingredients: 1 teaspoon coriander seeds 1/2 teaspoon yellow mustard seeds 3 tablespoons peanut oil 1/2 teaspoon curry powder (preferably Madras) 1 tablespoon minced peeled fresh ginger 2 cups chopped onions 1 1/2 pounds carrots, peeled, thinly sliced into rounds (about 4 cups) 1 1/2 teaspoons finely grated lime peel 5 cups (or more) low-salt chicken [...]