Puree tomato, shallot, vinegar, marjoram, rosemary, salt and pepper in a blender until smooth. Set aside 1/2 cup, covered, in the refrigerator. Scrape the remaining puree into a large, sealable plastic bag. Add steak and turn to coat. Refrigerate for 4 hours or up to 24 hours.
Preheat grill to medium-high. Remove the steak from the marinade (discard the marinade). Oil the grill rack (see Tip). Grill the steak 4 to 5 minutes per side for medium-rare or 6 to 7 minutes per side for medium, turning once and brushing the cooked side with some of the reserved sauce. When the steak is cooked, turn it over again and brush with more sauce. Transfer to a clean cutting board and let rest for 5 minutes. Thinly slice the steak crosswise and serve with any remaining sauce spooned on top.