This purée is loaded with vegetables, but mixed into an avocado and ham sandwich, your kid will never know.
To prepare Green Purée on the stovetop, pour about 2 inches of water into a pot with a tight-fitting lid. Put a vegetable steamer basket into the pot, add the broccoli, and steam for about 10 minutes, until very tender. Add the frozen peas to the basket for the last 2 minutes of steaming. Drain.
To prepare in the microwave, place the fresh broccoli in a microwave-safe bowl, cover with water, and microwave on high for 8 to 10 minutes (frozen florets take only 1 to 2 minutes), until very tender. Add peas for last 2 minutes of cooking. Drain.
Place the raw spinach in the food processor first and pulse a few times. This will reduce the spinach significantly. Next add the cooked broccoli and peas, along with 2 tablespoons of water. Purée on high until as smooth as possible. Stop occasionally to push the contents to the bottom. If necessary, use another tablespoon of water to make a smooth purée.
This recipe makes about 2 cups of purée; double it if you want to store more. Green Purée will keep in the refrigerator for up to 3 days, or you can freeze 1⁄4-cup portions in sealed plastic bags or small plastic containers.