Argentinian-Style Flank Steak and Chimichurri

It's been a while since I posted anything "meat," so I thought it was about time.
Grilled foods are such a nice summery option. The only problem is that I'm not exactly grill-proficient. I do like the grill- vegetables are fantastic and easy to gauge, hamburgers aren't difficult to tackle, and neither are things like a pork shoulder that have a low heat and extremely slow cooking time.

My problem happens to be those things that need a somewhat high heat and more controlled cooking time for a perfect medium-rare. Problem being that I can't seem to obtain the necessary control for long because the grill I use decides to suddenly drop in temperature. It's finished for the day, it's not going to do any more work.
Then the timing doesn't work out because the temperature decided not to cooperate.  You're at the point when you have meat that's partially cooked, but you have no idea exactly HOW cooked it is, and maybe you're not certain how long the temperature was at the desired level before it dropped... well, what is one supposed to do?
Rather than spearing the steak to check it's doneness and lose all the juices, I prefer something a little more consistent from the beginning.
For precision, I prefer to cook on the stove. See, I'm comfortable with that. A grill pan is great, but a heavy frying pan such as one made of cast iron will also work well. The grill flavor may not exactly be there (sorry), but a really nice sear can still be attained.
If you're happy with your grill and comfortable using it for something like this, have at it. I'm sure you'll be pleased.

I give instructions for medium-rare steak because that's what I like. (Although, quite honestly,  this time around I changed things a bit by not paying attention to what I was doing, heating the pan over high, walking away, then dropping the temperature to medium-high after I put the steak in the pan. This seems to be better instruction on a steak that's closer to medium than medium-rare. The real medium-rare instructions are below. My apologies, but there was no time for a "round two" to fix it for photographic purposes.)
That said, cooking your meat more rare or more done is completely up to you. I don't plan to give instruction on how to play Russian roulette food poisoning (do you trust your butcher?) or grill up some nice hockey pucks.  But I don't know that either of those require much instruction- and if that's what you like, it's your dinner.

One other thing is that the cooking method in the recipe is the one I always use for a flank steak: hot pan, salt and pepper the steak, cook on one side, turn and cook on the other, let the meat rest off the heat in the pan.  It's my basic flank steak how-to, and I like how it turns out.
The "different" thing in this case is the marinade and chimichurri (which tastes like green and garlic with a little bite).
Earlier on I had a recipe for some steak and chimichurri, but I think I like this version much better.

If you're looking for a different herby green sauce for flank steak, a fresh basil pesto might be nice.

Oh yes! Speaking to a vegetarian who thought the marinade smelled fantastic (after it sat a while but before the meat went in), we decided it had the potential to make a really nice vegetarian meal. Marinate some meaty vegetables (like mushrooms) and serve the chimichurri alongside...

You'll just have to imagine what the vegetables would look like. 

Argentinian-Style Flank Steak and Chimichurri
serves 4-6
Marinade adapted from a recipe in Gourmet, August 2008 (originally adapted from Abingdon Manor)

Marinade:
1/4 c (60 ml) vegetable oil (sunflower, peanut)
1/2 c (120 ml) white vinegar
1/2 c (32 g) chopped fresh cilantro (stems are fine to use)
3 large cloves garlic, minced
2/3 c (80 g) chopped onion
1 T (2 g, or 15 ml if weight is too small to measure) fresh minced thyme leaves 
2 t (1 g, or 10 ml) fresh minced oregano
1 1/2 t (5 g) ground cumin

1 1/2- 2 lb (680-907g) flank steak

Before cooking: kosher salt and freshly ground black pepper

Chimichurri:

1/4 c (60 ml) red wine vinegar

1/4 c (60 ml) olive oil

1/4 c (33 g) minced onion

3 cloves garlic, minced 

1 1/2 t (7 ml) lemon juice

1/3 c (24 g) minced fresh parsley, lightly packed

2 t (3 g, or 10 ml if weight is too small to measure) minced fresh oregano

a nice pinch of hot red pepper flakes

1/2 t (2 g, or 2.5 ml) freshly ground black pepper

3/4 t (6 g) kosher salt

In a large resealable plastic bag, place the oil, vinegar, cilantro, garlic, onion, thyme, oregano, and cumin. Mix the ingredients to combine well, and place the flank steak in the bag. Coat the steak in the marinade, remove excess air from the bag, and seal.  Of course, this could easily be done in a bowl, but you may have to turn the steak a few times so it all marinates evenly. Refrigerate 4-5 hours. 

While the steak marinates, make the chimichurri. 
Stir together all chimichurri ingredients in a medium bowl. Set aside and let stand at least 2 hours so the flavors meld. 

When ready to cook the steak, heat a large heavy frying pan or grill pan over medium-high heat a couple minutes. Remove the steak from the bag and wipe off excess marinade. Generously salt and pepper the steak and place the steak seasoned-side down in the hot pan. Salt and pepper the other side as the first side cooks. For a 2 lb. steak, cook 8 minutes per side for medium-rare. For a smaller steak, 1 1/2 lb., maybe 7 minutes per side.  
When the first side has finished cooking, flip the steak and cook on the other side. Remove the pan from the heat and let the steak rest in the hot pan about 10 minutes. 

Slice the flank steak against the grain and serve with the chimichurri.