1. Combine the marinade ingredients in a small bowl and set aside half the mixture. Place the roast in a ziplock bag and add the second half of the marinade.
2. Allow to marinate at room temperature for 30–60 minutes.
3. Preheat oven to 500 degrees Fahrenheit (260 degrees Celsius).
4. Place the tomatoes and dates in the center of a nine- by 13-inch (20- by 30-centimeter) roasting pan. Place the roast on top. Bake uncovered for 20 minutes.
5. Lower oven temperature to 200 degrees Fahrenheit (90 degrees Celsius). Brush the roast with the remaining sauce every 30 or so minutes until the internal temperature of the meat reaches about 130 degrees Fahrenheit (54 degrees Celsius). (Allow about 30 minutes per pound, but do not rely on timing. Use a thermometer.)
6. Carryover cooking will bring the temperature up a few degrees once it’s removed from the oven, so if you prefer more rare than medium rare, remove from the oven at 125 degrees Fahrenheit (52 degrees Celsius). If you prefer medium, remove at 135 degrees Fahrenheit (57 degrees Celsius). Let the meat rest for 10 minutes before slicing.