1. First, prepare the steak marinade: Into a measuring cup, add the mustard and blend it with the olive oil, dry red wine or red wine vinegar, garlic, salt and pepper. Stir well. Remove one tbsp of this mustard mixture and set aside. Add most of the chopped cilantro, all of the Herbes de Provence, stir well and set aside
2. Apply the marinade all over the steak. Set aside for 30 minutes, or place on a platter or in a large bowl and cover with cling wrap to refrigerate overnight, and for up to 24 hrs. For best results, let the meat come to room temperature before grilling
3. Preheat a well-oiled grill over medium-high heat if using a stovetop, or preheat and grease the grill before using your BBQ
4. Place the steak on the grill and sear each side for about 2- 5 minutes (time will depend on thickness of your steak). This is to seal the juices and brown the outside of the steak
5. Reduce the heat to medium and grill until the steak is done to your liking
6. When done, place the steak on your cutting board and let rest for 10 minutes before cutting, against the grain, into sections
7. While steak is resting, prepared the seasoned tomatoes. Into the bowl add the cut cherry tomatoes, the capers, chopped cilantro and the tbsp of mustard mixture set aside from step 1. Toss gently to coat all the tomato pieces
8. After cutting the steak, place on a serving platter and distribute the prepared cut tomatoes on top. Enjoy!