Combine vegetables in a large saucepan and cover with 2 inches of water. Bring to a boil over high heat, then reduce heat to medium low and simmer until vegetables are fork tender, about 6 minutes.
Remove vegetables with a slotted spoon, reserving cooking liquid, and place in a blender.
Add 1 cup of the cooking liquid and blend until mixture is smooth.
Let cool slightly, then divide into 1/4-cup portions, place in airtight containers, and refrigerate up to 5 days or freeze up to 6 weeks until ready to use.
