Cook the potatoes and green beans in whatever manner you wish. (I steamed mine in the microwave.)
Tear the basil leaves and place them and the lemon juice in the bowl of a food processor along with a couple pieces of cooked potato.
Pulse a few times to chop everything and add water a little at a time to help the dressing come together.
Toss the dressing with the cooked potatoes and green beans. Stir in the sunflower seeds and lemon zest.
Season with salt and pepper to taste.