In Costa Rica, this popular breakfast bean dish is called gallo pinto, which means spotted rooster, referring to the dark beans amid the pale rice. We call for cooked barley here, but you can use whatever leftover cooked grain you may have on hand.
Heat oil in a medium skillet over medium heat. Add bell pepper, scallion whites, and cumin; cook, stirring often, until softened, 1 to 2 minutes. Add beans, cooked barley, broth, and salt. Cook until most of the liquid is absorbed, 3 to 5 minutes. Stir in scallion greens and hot sauce. Divide between 2 bowls.
Place 1/2 cup water and 1/2 tsp. vinegar in a microwave-safe small bowl. Carefully crack 1 egg into the water so it is completely submerged. Cover with a microwave-safe plate and microwave on High until the egg white is firm and the yolk is still somewhat runny, about 1 minute. (If necessary, continue to microwave, checking every 10 seconds.) Remove the egg with a slotted spoon, pat dry and place atop the bean mixture in 1 bowl. Repeat with the remaining 1/2 cup water, 1/2 tsp. vinegar, and egg.
Top each bowl with 1 Tbsp. cheese and 1/4 avocado. Sprinkle with cilantro, if desired.
To make ahead: Prepare beans and barley (Step 1) up to 3 days ahead and refrigerate. Reheat in the microwave and continue with Step 2.