Bring a large pot of salted water to a boil. Cut the butter into small pieces and keep it cold. Set up your blender so it's ready to go.
Once the water is at a rolling boil, add the frozen peas and continue to boil for 2-3 minutes or until completely soft.
Immediately scoop the peas out of the boiling water using a spider strainer and place them into the blender. Add a few tablespoons of the hot water, the salt, the sugar and the zest from two lemons into the blender.Blend until the blades catch the puree and you can see the puree turning in the blender. With the blender still running, add the chunks of cold butter in stages until completely melted.
Once the puree is smooth, transfer it to a bowl with an ice bath bowl underneath it. Stir with a spatula until cool.
Once cooled, store your pea puree in a sealed mason jar with a lid in the fridge for up to 5 days.
Notes
You may need to add a little more water to the peas to allow the blender blade to catch the puree. Add enough water for the blades to catch but be careful not to add too much water.Cooling the puree over an ice bath will prevent the colour from going grey.