Cut the beef across the grain into roughly ½-inch-thick strips.

In a wok or large cast iron or stainless steel skillet, heat 2 tablespoons (30ml) oil over high heat until heavily smoking. Meanwhile, season beef all over with salt.

Working in batches, add just enough beef to the pan to sear it heavily without steaming in its own juices. Spread the beef around so the pieces are evenly spaced apart and allow to cook until very well seared and charred on one side, 30 seconds to 1 minute. Stir and toss beef so that it cooks all over, about 30 seconds longer. Using a spatula, transfer beef to a platter to rest. Repeat with remaining beef.

When all the beef is cooked, return the empty pan to high heat. Add 1 tablespoon (15ml) oil and heat until smoking. Working in batches, add just enough red onion so that it sears and browns rapidly without steaming, about 30 seconds. Toss a few times until the onion is crisp-tender. Using a spatula, transfer onion to a platter. Repeat with remaining onion.

Return the empty pan to high heat, add 1 tablespoon (15ml) oil, and heat until smoking. Working in batches if necessary, add scallions and cook, without stirring, until seared on bottom side, about 30 seconds. Push scallions to the side and add peppers. Cook until seared, about 30 seconds longer.

Push scallions and peppers to the side and add tomatoes to the pan, allowing them to sear on one side, about 30 seconds. Add garlic and ginger and cook, tossing and stirring constantly, until lightly sautéed and fragrant, about 15 seconds. Add soy sauce and vinegar and toss to combine.

Return beef and all accumulated juices to the pan along with the red onions. Add cilantro. Toss over high heat to combine well, seasoning with salt and pepper as you go. Remove from heat.

Spoon stir-fry onto plates with a mound of cooked rice and French fries and serve right away.