Cut beef in thick slices and marinade for 30 minutes.
Heat 2 tbsp oil in wok, fry onions and garlic. Add in beef slices and stir fry well, then add in enough hot water to cover beef over 1 inch.
Simmer beef over low heat for 1 hour then remove from heat and let beef cool. The return to heat and simmer for another hour and let cool again.
Take out beef and onions from wok, and finely mince.
Heat some oil in wok, fry the minced beef and onions and add in celery. Stir well and cook until sauce starts to dry up. Take out and reserve for use.
Poach clean vegetables in water, take out and rinse under cold water. Soak all moisture with a piece of kitchen towel, and mince vegetables.
Heat another 1 1/2 tbsp of oil in wok, then stir fry spinach along with seasonings, and arrange to sides of plates.
Place minced beef and onions in middle, and scatter fried pinenuts over beef and serve.