Any pureés leftover can be stored and frozen in an airtight container.
Green Vegetable Pureé
170g (6 ounces) spinach or other leafy greens, such as kale, arugula, chard, mustard, or a mix, any ribs and tough stems removed
Bring a medium pot of water to a boil. Add the greens and blanch until vibrant and tender, about 20 seconds. Drain immediately and rinse under cold water to stop the cooking or plunge into a bowl of ice water and drain.
Transfer the greens and their residual water to a small blender and pureé until very smooth. If needed, add splashes of water, 1 Tablespoon at a time, until they are easily blended.
Pink Vegetable Pureé
2 medium red beets, cleaned
Heat the oven to 400℉/205℃. Cut the stems and roots of the beets so the flesh is exposed and they stand upright. Place them cut-side down in a small, deep baking dish or load tin and add enough water to cover the bottom by 1/4 inch.
Cover lightly with foil, prick a few holes in the top, and roast until very tender and easily pierced with a knife, 45 to 60 minutes. Check the beets halfway through; if the bottom of the baking dish look dry, add a bit more water.
When the beets are still warm but cool enough to handle, remove the skins with a paper towel and roughly chop. Transfer to a small blender and pureé until smooth. If needed, add splashes of water, 1 Tablespoon at a time, until they are easily blended.
Orange Vegetable Puree
2 large red bell peppers
Set the oven broiler to high. Cut the peppers in half lengthwise. Remove the seeds and stems, then arrange the halves cut sides down on a foil-lined sheet pan. Broil the peppers for 25 minutes, rotating the pan halfway through, or until the skins are almost completely blackened.
Transfer the peppers to a bowl and cover lightly with a dish towel. Let them steam for 10 minutes. When the peppers are cool enough to handle, peel away the skins. Transfer to a small blender and pureé until smooth.