Heat a large frying pan over high heat and add your olive oil.
Season the ground beef and cook until browned and well done.
Remove from pan and dispose of leftover fats in pan.
Place the toasted sesame oil in the pan and heat over medium heat.
Add the garlic, ginger and chili and cook for 1 minute.
Be careful not to overcook the garlic as it will become bitter.
Add the sweetener and cook for a further minute.
Return the beef to the pan and stir to combine.
Add the fish sauce, lime juice and zest and combine well.
Stir over the heat for another minute and then remove from the heat.
Toss the spring onion greens through at the last minute.
To make the dressing, combine all of the ingredients in a jar and shake well.
Serve spoonfuls of the spicy beef in lettuce cups, topped with a drizzle of dressing and extra chili, if desired.
The beef will keep in a covered container in the fridge for up to one week.
It can also be portioned and frozen.