Sweet and Sour Thai Style Vegetables (v)

My moogi made this for me and Lex tonight and it was deeeeeelicious.

For 4-6 portions you need:
1 onion, roughly chopped
2 carrots, peeled and sliced
1 head broccoli, cut into florets
1 red pepper, cut in to chunks
1 tin pineapple, cut into chunks (reserve the juice)
1/2 head chinese leaf, finely shredded
1/2 pack baby corn, cut into bite sized pieces

2 tbsp soya sauce (mushroom soya sauce is the best one to use apparently but I don't think the world will stop turning if you use dark or light soya sauce...)
reserved pineapple juice
4 tbsp tomato ketchup

Place everything in a wok with a lid and heat. Cook for 5-10 mins, covered, till the veggies are tender. Serve with jasmine rice.