1.Combine sugar, 1½ tablespoons soy sauce, sherry and egg yolk and stir well. Cut meat into 2.5 cm cubes, place into soy sauce mixture and stir until meat is coated. Cover and leave for one hour, stirring occasionally.
2.Drain meat from marinade, reserve liquid. Toss meat lightly in cornflour; heat oil and cook meat until golden brown and cooked through (about seven minutes). Do this in several batches so meat browns evenly; drain well.
3.Prepare the vegetables – peel and slice onion, slice shallots diagonally, slice pepper thickly and remove seeds, slice mushrooms and celery, and cut the cucumber into quarters, lengthwise, removing the seeds and then slicing.
4.Heat three tablespoons oil in large pan, add all the prepared vegetables and saute for three minutes. Drain pineapple and add pineapple syrup to pan with marinade from meat, remaining soy sauce, tomato sauce, vinegar and crumbled stock cube.
5.Blend extra cornflour and water, add to pan and stir until sauce boils and thickens. Add pineapple pieces, season with salt and pepper, before adding the pork and stirring until combined.