In a small vessel, whisk together chili powder, cumin, garlic powder, salt, and black pepper.
Apply the spice rub uniformly to all surfaces of the flank steak.
Heat olive oil in a cast-iron skillet over medium-high heat until shimmering.
Place steak in the skillet and sear for 4 to 5 minutes per side until an internal temperature of 135°F (57°C) is achieved for medium-rare.
Remove steak from heat and allow to rest on a cutting board for 5 to 7 minutes to retain juices.
In a large mixing bowl, fold the chopped cilantro and lime juice into the warm cooked rice.
Slice the rested steak against the grain into thin strips.
Construct the bowls by distributing the cilantro lime rice evenly among four containers.
Arrange black beans, corn, cherry tomatoes, and sliced steak over the rice base.
Top each bowl with avocado slices, shredded cheese, and a dollop of sour cream.