Pasta with String Beans & Arugula

My cousin Lois gave me this recipe & I make it often.  It's easy and you can basically add whatever ingredients you have in the fridge.  I made this tonight for Matt & Lindsay and they liked it...which I take as a big compliment since they can actually cook :)

Here's the recipe as my cousin gave it to me.  But I always add chicken.

Ingredients
4 ounces green beans, trimmed
4 ounces yellow wax beans, trimmed (i used the ones we bought at the farmer's market!)
1 lb curved pasta (such as conchiglie, orecchiette, etc)
1/2 teaspoon lemon zest
1/4 cup fresh lemon juice (~2 lemons)
1/2 cup olive oil
1 ounce pine nuts, toasted
1/2 cup grated parmesan cheese
1 and 1/2 cups baby arugula
(and shredded cooked chicken, if you like...)

Directions
Cook beans in boiling salted water, about 4 minutes.  Drain & rinse with cold water.  Cook pasta until al dente.  Whisk lemon zest, juice & 3/4 teaspoon salt.  Add oil in a slow, steady stream, whisking until emulsified.  Drizzle over pasta and toss until well-coated.  Add beans, pine nuts and grated parmesan (and chicken, if you're using it).  Toss until evenly distributed.  Fold in arugula and top with extra parmesan.