For the XO sauce: heat half of the oil in a wok or saucepan set over a very low heat. Add the chopped garlic, followed by the shallot and lemon grass. Poach everything in the oil for 5-10 minutes stirring often.
Add the remaining oil to the pan and stir in the dried shrimps, ham, and chili flakes.
Continue frying over a low heat until the seafood takes on a golden hue and the ham becomes crisp.
Remove the pan from the heat and leave to cool. Transfer everything to a large glass jar secured with a lid. Leave everything to steep for a minimum of 2-3 hours.
This sauce improves with age and is best left to steep for a couple of weeks in the fridge or a cool place. A little goes a long way - use this sauce as a perky seasoning for stir-fries, noodles and rice dishes.
For the stir-fry: heat the rinsed wok over a high heat and add the sesame oil.
Tip in the snow peas and peppers and stir-fry for a minute before removing from the pan.
Add the shrimp, sugar and white pepper and continue frying for 2-3 minutes.
Return the peppers and sugar snaps to the pan and stir in enough XO sauce to give a spicy kick - you'll probably only need a tablespoon or so. The rest of the sauce can be used for other South East Asian dishes.
Combine the cornstarch with 2 tbs water and add to the pan, stirring all the time. This will bring all the juices together. Serve straight away with rice or noodles.