1. You can go very traditional and use luncheon meat if you wish. Instead of pork belly, you could also use other cuts of pork but not those used for stewing.
2. I used a packet of hard tofu which is suitable for stir fry. This is harder than firm tofu. If you can only find firm tofu, you would need to firm up the tofu a little bit more before cutting it.
To firm up the tofu, place the tofu on a cutting board next to the sink with the side away from the sink lifted slightly. Place a flat plastic container or a tray on the tofu with a small weight on it. Leave for 10-15 minutes. This will press the tofu and let excess water out of tofu.
Silken tofu is not suited for stir fry as it can easily crumble.
3. If you would like to add bean sprouts and/or julienned carrots, I would suggest that you reduce the amount of tofu by 1/3. Use 50g (1.8oz) each of bean sprouts and carrots. Alternatively, you could simply add these vegetables and increase the quantity of flavouring ingredients.
Carrots should be added before bitter melon and bean sprouts should be cooked after bitter melon.