Prepare all your ingredients.
Heat a fry pan over high heat, then add the oil. Fry the onion and garlic for 30 seconds.
Add the beef, salt and pepper. Fry until nearly all brown. (1-2 minutes).
Add the celery to the pan and fry for 1 minute.
Add the crushed tomatoes, fish sauce and sugar. Stir until combined and the sauce is bubbling.
Check the seasoning of your sauce. If it needs more salt / flavour then add more fish sauce. If the sauce is too tangy, add more sugar.
Serve with rice.