Combine Espresso Balsamic, mustard, Chipotle Olive Oil, shallots, garlic, salt, and pepper; whisk to make the marinade. Rinse sirloin, pat dry, and place in marinade covered for at least 2 hours.

Heat the grill to medium-high heat. Pat the steak dry and grill 4-6 mins on each side. Baste with the marinade while grilling, reserving ½ cup. Remove sirloin from heat and let rest for 5 mins before slicing.

Pour remaining marinade in a small saucepan and bring to a boil, then reduce to a simmer for about 2 minutes, allowing it to thicken. Slice sirloin thinly against the grain and serve with a drizzle of the sauce