Optional: remove the strings from both edges of the pea pods by gently pulling them starting at the stem.
place the peas in a steamer basket set over 1 1/2 inches of boiling water, cover, and steam until they are just crisp-tender, 3-5 minutes.
Drain the pease in the sink and immediately run cold water over them. Transfer the peas to a clean, dry, dish towel and pat them dry. Place in a large bowl and add the cucumber.
Put the oil, walnuts, lemon juice, water, dill and cayenne pepper into a blender. Blend until smooth.
Pour the walnut-dill dressing over the cucumbers and peas and toss to combine. Season with salt and pepper and serve.