Place the steak on a cutting board, cover with plastic wrap, and lightly pound with the textured side of a meat mallet to lightly tenderize it. Slice it thinly (about ¼-inch) against the grain into 2-inch strips. Place the beef in a bowl, sprinkle with the paprika, and toss to coat.
Heat 1 tablespoon oil in a large skillet over MEDIUM-HIGH heat. Add half the beef in a single layer and cook until browned. Use kitchen tongs or a slotted spoon to transfer to a plate and repeat with the remaining beef.
Reduce the heat to LOW and add the garlic, ginger, and tomato paste to the oil left behind in the empty skillet. Cook, stirring, for 1 to 2 minutes. Add the beef broth, soy sauce, sugar, and black pepper and stir to combine. Return the beef and any accumulated juices to the skillet. Bring to a simmer, then reduce the heat to LOW, cover, and cook for 25 to 30 minutes, or until the beef is tender.
Add the bell peppers and onion. Cover and cook for an additional 5 minutes, or until crisp-tender.
In a small bowl, whisk together the cornstarch and water. Add to the skillet and cook, stirring, until the sauce has thickened. Remove from the heat.
Serve over rice if desired.