Heat grill to medium-high. In a small bowl, combine espresso, chili powder, garlic powder, 3/4 tsp of the salt, the sugar, paprika and 1/4 tsp of the pepper. Sprinkle 1 tbsp of the rub over one side of steak and press in with your hands. Turn steak over and repeat. Reserve remaining rub for another use.
Season zucchini with 1/4 tsp of the remaining salt and remaining 1/8 tsp pepper. Thread mushrooms onto 2 skewers. Brush mushrooms and yellow pepper pieces with balsamic dressing. Grill vegetables for 6 minutes, turning once. Grill steak for 6 to 8 minutes, depending on thickness, turning once.
Meanwhile, microwave rice for 90 seconds. Remove steak from grill and let rest for 5 minutes. Quarter mushrooms and dice yellow pepper. Toss in a bowl with rice and remaining 1/4 tsp salt. Slice steak and serve with zucchini and grilled veggie rice.
Don’t throw away leftover rub. It can be mixed into meatloaf, rubbed onto chicken thighs or sprinkled over salmon before baking or roasting.