Bring a saucepan of salted water to a rolling, constant boil.
Prepare a bowl of ice-cold water next to it.
Cut the broccoli into small to medium-sized florets, try to keep them all to a similar size to ensure an even cooking time. Trim as much of the stalks off as you can.
Cut the asparagus into short pieces approximately 1-2 inches long. If the end of the asparagus spear seems tough and woody, remove it.
First, cook your broccoli by placing the florets into the boiling water and cooking for 4 or 5 minutes until they are tender but still a vibrant green colour.
Remove them immediately to the iced water with a slotted spoon to halt the cooking process and leave them there until they have completely cooled.
Now cook the asparagus, which cooks much faster and will need one minute exactly before also being placed in ice water.
Reserve the cooking water as we will need it in our truffle broccoli asparagus puree.
Add the cooled broccoli and asparagus to the liquidiser and add a small amount of cooking water to help get things moving.
Start the liquidiser and add more of the reserved cooking liquid a tablespoon at a time until it is able to blend everything down to a puree. Be patient and give the liquidiser time to do its work, don't add too much liquid too soon. Keep blending until you reach a smooth texture with no flecks of the broccoli or asparagus present.
Now add your truffle oil. Adding a few drops will suffice as it has a strong flavour, and continue to blend the puree so it emulsifies.
The result will be a glossy, vivid green truffle broccoli asparagus puree - season with salt and pepper to taste at this stage and add more truffle oil if you think it needs it.
A note on consistency, this puree should be a thick liquid that holds its shape if you put a spoonful on a plate and doesn't run. if you reach soup consistency, you've gone too far.
Place the truffle broccoli asparagus puree in a saucepan to reheat, or store in an airtight container until needed.