In a 12-inch stainless-steel skillet, heat 1 tablespoon oil over high heat until just smoking. Add half of the beef, spreading it out in a single layer. Season lightly with salt and pepper and cook without moving until lightly browned on first side, about 1 minute. Toss and continue to cook, stirring frequently, until fully browned, 2 to 4 minutes. Transfer to a large bowl. Repeat with 1 tablespoon oil and remaining beef.
After all meat has been removed from the pan, lower the heat to medium and if skillet is dry, add the remaining 1 tablespoon of oil if necessary. Add onions and bell pepper and cook, stirring occasionally, until softened, about 3 minutes.
Stir in the garam masala, garlic, and ginger and cook until fragrant, about 1 minute. Add the tomato paste and cook, stirring to incorporate, until paste darkens, about 1 minute.
Add tomatoes, stir to combine and cook, stirring frequently, until the tomatoes break down and vegetables soften into a cohesive, slightly chunky sauce, 7 to 8 minutes.
Once the sauce has thickened and the vegetables are cooked down, toss the seared beef back into the skillet, stirring to coat the meat in the sauce. Cook until warmed through, 1 to 2 minutes.
Stir in cilantro just before serving. Serve with ugali or white rice.
