How to Make It
In a small skillet, toast the pine nuts over moderate heat, tossing, until golden, about 5 minutes; transfer to a food processor and let cool completely.
Add the parsley, garlic, lemon zest and lemon juice to the food processor and pulse until the parsley is very finely chopped. With the machine on, gradually add the olive oil and process until the pesto is nearly smooth. Season with salt and pepper and scrape into a large bowl.
Put a steamer basket in the bottom of a pot. Fill the pot with 1 inch of water, add salt and bring to a boil. Add the green beans, cover and steam until bright green and crisp-tender, 8 to 10 minutes. Drain the beans and transfer to the large bowl. Toss with the pesto and season with salt and pepper; serve with lemon wedges.