Pour the tequila, cream of coconut, lime juice, and 2 tablespoons of the sugar syrup in a cocktail shaker or large mason jar with a lid. Shake it well to combine everything. Then add in 3 drops of sriracha hot sauce, and shake everything together again.
Dip a spoon in to taste the mixture. There should be just a little heat. If you want more heat you can add more sriracha a drop at a time.
Coat the rims:
Combine the salt and lime leaf powder in a shallow dish (wide enough to fit the rim of your margarita glass into.) Have another shallow dish ready with sugar syrup in it.
Dip the rims of the glasses first in the sugar syrup and then in the salt-lime mixture, dabbing the rim until it has an even coating of salt on it.
Pour the drinks:
Place ice cubes in each glass carefully so you won't knock salt off the rims. Pour the margarita mixture into each glass. Serve the drinks immediately.
Cream of coconut gives this cocktail sweetness and rich coconut flavor. Look for cream of coconut in the section where drink mixers are kept, in grocery stores or liquor stores. (This is not the same as coconut cream or coconut milk.)
I don't recommend coconut milk because I found that coconut milk curdles when combined with tequila - and that means unappealing curds will be floating in your drink! Sweetened cream of coconut blends smoothly and is why I chose it for this cocktail.
Mix this margarita just before serving. The ingredients tend to separate when made in advance.
Kaffir lime leaf powder can be found in spice stores online and in bulk spice sections of natural foods stores. If you don't have any you can use just salt on the rims, or grind salt together with lime zest in a food processor.
If you're like me and don't own any margarita glasses (who has the space to stash all those cocktail-specific bar glasses??) my go-to is always the pint-sized mason jars! I have a ton of them on hand and they're perfect for a small drink.
Consider stashing your margarita glasses in the freezer ahead of time to get them really cold for your drinks.