For the Chimichurri: While the steak rests, place the cilantro leaves, onion, 4 cloves garlic, juice of 1 lime, and 1/3 cup vinegar to a blender and puree until combined. With the blender on low speed, drizzle in the 1/4 cup olive oil in a low stream. Remove the sauce from the blender and stir in the red pepper flakes and salt to taste.
For the Chipotle Cream: Combine the sour cream, chipotle pepper, adobo sauce, juice of 1/2 lime, and a pinch of salt.
Place the steak, 3 cloves garlic, 2 tablespoons each olive oil and red wine vinegar, 1 teaspoons salt, 1/2 teaspoons black pepper, and dijon mustard in a resealable bag. Rub the ingredients into the meat and place in the refrigerator to marinate 2 hours.
After 2 hours, remove the meat from the bag and pat dry to remove any excess moisture. Lightly season both sides with salt and pepper. Set aside.
Spray an indoor, stovetop grill with nonstick cooking spray and preheat on medium-high heat. Place the steak on the preheated grill and grill about 6 minutes per side for medium rare. After grilling the steak, cover with tented foil and allow to rest for 10 minutes before thinly slicing across the grain.