Preheat a grill pan over medium-high
heat. In a medium saucepan,
heat the EVOO, 2 turns of the pan,
over medium-high heat. Add the
onion and garlic; cook until softened,
about 5 minutes. Add the tomatoes
and chicken stock and heat through,
about 5 minutes. Stir in the vinegar,
brown sugar, Worcestershire sauce
and lots of pepper. Lower the heat
and simmer, stirring occasionally,
until thickened, 7 to 8 minutes.