Mix up the ingredients for the sauce in a bowl. Heat a pot of water on the stove and cook the soba noodles. While that is going on, heat some sesame oil in a skillet, and fry the pork until it is cooked through, tossing it with some stir-fry sauce just before it's done. Add the carrots and keep frying until softened, about 3 minutes. Add the cabbage and fry some more until it's wilted. Add the pineapple and sauce, and simmer for a few minutes until the sauce thickens. Drain the soba noodles and add to the skillet. Mix together to incorporate the stir fry and noodles.