Cook the frozen French fries in an air fryer or oven according to the package directions until crisp. Keep them warm while you make the stir-fry.

Pat the steak dry with paper towels. Season it with the salt and black pepper. Stir together the soy sauce, red wine vinegar, and ají amarillo paste in a small bowl.

Heat 1 tablespoon of oil in a large wok or heavy skillet over high heat until it looks shimmering. Add half of the steak in a single layer and sear without moving it for about 1 minute. Stir-fry for 30 to 60 seconds more, until browned. Transfer to a clean plate and repeat with the remaining steak.

Add the remaining 1 tablespoon oil to the hot skillet. Add the onion and stir-fry for about 2 minutes, keeping the wedges slightly crisp. Add the garlic and stir for 20 seconds.

Add the tomatoes and cook for about 1 minute, just until they begin to soften but still hold their shape. Return the steak and any juices to the skillet.

Pour in the soy-vinegar mixture. Toss constantly for 30 to 60 seconds, until the beef is coated and the sauce lightly glosses the vegetables. Taste carefully and add a small pinch of salt only if needed.

Spoon the hot rice onto four plates. Divide the beef and vegetables over the rice, add the crisp fries alongside or over the top, and finish with cilantro if using. Serve right away.