Brown pork in a large heavy pan with oil. Cook until evenly browned. Remove excess fat.
Add stock into the pan and heat. Mix in sugar and soy sauce then cover. Simmer for about 2 hours or until meat is done.
Transfer meat in a plate to cool then slice.
Prepare spinach by washing the leaves and discarding any tough stems. Add it into the pan with the warm gravy. Stir lightly until the leaves are soft but bright green in color.
Drain spinach and place it on a serving platter. Top with pork slices and serve.