If you don't have leeks, feel free to use onions.How to trim the bottom of asparagus stalks: Hold the asparagus stalk and bend the bottom until you find the part where it breaks easily. I usually break one and then trim all the others the same length using a knife.I tend to make my soups thick, so add more water or broth as necessary to get it to the consistency you prefer.
1poundasparagus, trimmed and cut into bite-size pieces
2leeks250 g or 1/2 pound, trim the bottoms and green parts, and dice
1cauliflower headabout 500 g or 1 pound, cut into bite-size pieces
Preheat your oven to 425°F (220°C, or gas mark 7).
Prepare a baking sheet with parchment paper, or a non-stick mat.
Place the asparagus, leeks, cauliflower, 1/4 teaspoon of salt, and oil in a bowl and mix the vegetables to cover them with oil.
Spread the vegetables out across the baking sheet and bake for 25 minutes, or until the vegetables are tender.
Cool the vegetables for a few minutes. Optionally, reserve some of the roasted vegetables to serve on the top of the soup.
Add about half of the roasted vegetables and 1/2 teaspoon of salt to a high speed blender or food processor. Add the water or broth and blend in batches until it is creamy, adding more vegetables as you go. You may want to add more salt to your liking.
Serve very warm.
Store leftovers in the refrigerator for a few days, or freeze for a few months.