Warm olive oil in a medium pot over medium heat. Add scallions and saute for about 2 minutes.
Add zucchini, peas, salt, and water; bring to a boil over high heat. Cover pot, reduce heat to low, and simmer for 6 minutes or until zucchini is tender and peas are cooked.
Remove from the heat. Stir in the dill and lemon juice, and set aside, uncovered, for 10 minutes before blending.
Add protein powder, and blend soup in batches in upright blender for 1 to 2 minutes, or until completely smooth and velvety. Add a little more water if needed to get desired consistency. Season to taste with salt and black pepper.
When using frozen peas, leave them out to thaw while making the soup; add them after simmering the zucchini for 6 minutes, cover pot and cook 1 additional minute before removing from heat and proceeding with the recipe.
Adapted from At Home in the Whole Foods Kitchen by Amy Chaplin