Buying baby food is as simple as picking the cans and containers off the grocery-store shelf, but making it at home can be just as quick and easy. If the puree is too thick, you can thin it with breast milk, formula, or boiled water.
Arrange carrots on a steamer rack in a large pan over 1 inch of water. Cover, and bring to a boil. Reduce heat. Steam until tender, about 12 minutes. Plunge carrots into cold water to stop cooking. Pulse in a food processor, or pass though a food mill fitted with a medium disk. Add formula, breast milk, or boiled and cooled water as needed. Fill 1/4-cup plastic containers or ice-cube trays with puree.