Heat the oil in a skillet over medium heat. Cook, turning once or twice, until the potatoes and carrots are lightly browned. Remove from pan and pat dry with paper towels.

Cook for 30 to 45 seconds after adding the bell peppers. Remove from pan and pat dry with paper towels.

Remove all but about 2 tablespoons of the oil from the pan. Increase the heat to medium-high. Cook for 1 to 2 minutes, then turn and cook for another 1 to 2 minutes, or until lightly browned. Remove from the heat and set aside to keep warm.

If necessary, add another tablespoon of oil. Cook, stirring frequently, until the onions and garlic are softened.

Add the beef.

Cook for 1 to 2 minutes after adding the fish sauce.

Pour in the crushed tomatoes, water, and tomato paste. Bring to a boil, stirring constantly until evenly distributed.

Reduce the heat to low, cover, and cook for 1 1/2 to 2 hours, or until the beef is tender. If the sauce is drying out before the meat is tender, add more water in 1/2 cup increments as needed.

Cook for another 4 to 5 minutes, or until the potatoes and carrots are tender and the sauce has thickened and reduced to your liking.

Cook for about 1 minute, or until the bell peppers are tender but still crisp.

Season to taste with salt and pepper. Serve immediately.