Flank Steak with Parsley-Garlic Sauce

This is a truly tasty recipe that I've made a few times!  Thank you very much, Martha Stewart!  I found the recipe here, but I'll reprint it below for you.  Most recently, I served this with Aunt Trisha's smashed potatoes (recipe here) and some watermelon...except I only made half of the parsley-garlic sauce because I find that if I make the whole batch, I have tons extra.  Easy, tasty -- what more could you want?

Prep: 20 minutes
Total: 25 minutes
Serves 4

Steak Ingredients
1.5 lb flank steak (you could also use skirt or hangar steak cuts)
Coarse salt and ground pepper
1 TBSP olive oil

Parsley-Garlic Sauce Ingredients 
1/4 cup olive oil
1 or 2 cloves garlic
1 bunch flat-leaf parsley, stemmed (about 4 cups) (this is pretty important -- take the time to remove the stems from the parsley...if you leave them in, the sauce will taste too much like parsley)
3 TBSP oregano leaves
3 TBSP white wine vinegar

2 TBSP water

1/2 tsp salt

1/8 tsp red pepper flakes

Preparation: 

1. (Step 1 is for the steak)  Generously season both sides of flank steak with salt and pepper.  Heat 1 TBSP oil in a large skillet over medium-high heat.  Cook steak 5-8 minutes per side for medium-rare.  Transfer to a board; let rest, covered, 10 minutes.  Thinly slice against the grain.

2. (Step 2 is for the sauce)  Meanwhile, make sauce: In a food processor, pulse garlic until finely chopped (I start with it chopped, so I skip this step and just pile everything in).  Add parsley, oregano, vinegar, pepper flakes, 1/4 c. olive oil, water and salt.  Pulse until herbs are finely chopped.  Serve with steak.