Fill a pot with a few inches of water and place a steamer basket in it. The water should not touch the basket.
Wash and cut 1 cup of cauliflower. Place the cauliflower in the steamer basket, cover the pot and steam on medium heat for 5 minutes.
Next, add 1/2 cup of frozen peas to the steamer basket and steam for another 5 minutes. Test it to make sure the cauliflower is fork tender, then remove it from heat.
After the vegetables have cooled slightly, add them a blender along with the dill. Puree until smooth, adding liquid as necessary.