Step 1

Season the meat with salt and pepper.

Step 2

For the chimichurri, combine the red onion, vinegar, salt and olive oil and let it sit for about 5 minutes. Add the remaining ingredients and mix; set aside in the refrigerator until ready to use (can be made a few hours ahead).

Step 3

Place the onions, beef and tomatoes onto the skewers.

Step 4

Prepare the grill on high heat. Grill the steaks to desired doneness, about 2 to 3 minutes per side for medium-rare. Transfer steaks to a platter and top with chimichurri sauce.