In a small bowl, whisk together the olive oil, adobo sauce, cumin, smoked paprika, garlic powder, onion powder, salt, and pepper.
Rub the marinade all over the sirloin tip steak and let it sit for 20 minutes at room temperature to absorb the flavors.
Preheat your grill to medium-high heat and lightly oil the grates to prevent sticking.
Grill the steak for 5-6 minutes per side for medium-rare, or until it reaches your desired internal temperature.
While the steak grills, place the sliced bell peppers and red onions on the grill in a basket until they are tender and charred.
Remove the steak from the grill and let it rest for 10 minutes before slicing thinly against the grain.
Prepare the smoky crema by mixing the Greek yogurt, lime juice, and a pinch of cumin in a small dish until smooth.
Assemble the platter by arranging the sliced steak, grilled vegetables, brown rice, black beans, and avocado slices.
Garnish the entire platter with fresh cilantro and serve with the yogurt crema on the side.