Carrot ginger soup - chinese grandma

Ingredients

• 3 tablespoons butter
• 1 large onion, chopped (about 2 cups)
• 2 pounds carrots, chopped (7-8 cups)
• 4 tablespoons fresh ginger, grated (approximately 1 2-ounce ginger root)
• 6 cups chicken (or vegetable) broth
• 1/4 cup orange juice
• Salt and pepper to taste