Heat 1 tablespoon oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add onion and ½ teaspoon salt and cook until onion is softened and beginning to brown, 5 to 7 minutes. Stir in corn and cook until lightly browned, about 4 minutes. Stir in rice, garlic, cumin, and cayenne and cook until fragrant, about 30 seconds.
Stir in broth and bring to simmer. Cover, reduce heat to medium-low, and simmer gently, stirring occasionally, for 25 minutes.
Stir in beans. Cover and simmer, stirring occasionally, until liquid is absorbed and rice is tender, about 30 minutes. Season with salt and pepper to taste.
Combine remaining 1 tablespoon oil, tomatoes, scallions, cilantro, and lime juice in bowl and season with salt and pepper to taste. Spoon tomato mixture over rice and beans and serve.