*Copied and pasted from my 'Baby Back Ribs' thread (More olive oil and gin, depending on the amount/size of onion). I've found that gin, if implemented correctly, is quite complementary.
I first learned of implementing use of gin from someone who shared his method. The flavors provide a subtle taste that compliment sauces nicely.
If you want to experiment with it, try slicing a good-sized onion into fairly thin slices and putting them in a sauce pan adding just enough olive oil to cover the slices, maybe a little bit more, approximately a tablespoon. The thicker the pan used the better. Under medium heat warm the onion pieces until they become softened. Next, pour in four or five tablespoons of Bombay Sapphire Dry Gin or more depending on the amount of the onion used with medium-high heat. Some garlic cloves can be added, I prefer to use shallots. This particular gin has a remarkable flavor profile for barbecue.
Once it is about dry or most the liquid has evaporated, incorporate in a half tablespoon or so of dark brown sugar, pan removed from the burner using a rubber spatula. At this point, with reduced heat to medium-low, stir for about two or three minutes till onion and shallot/garlic, sugar mixture is caramelized good to the point where it all begins to singe a bit. You want to continue to stir with a wooden spoon steady throughout most the whole process. A sharp-edged utensil can be used to chop into smaller pieces.
Makes a wonderful addition to sauce or even topping a grilled steak. Some fresh pepper slices added work well for that. I've found that the trace amounts of flavor added to the wood seem to add another dimension to the flavor too most probably attributed mostly to the steam. The wood shouldn't be dripping wet either just moistened. I've also added (a little bit) of gin to the bath set below brisket and in brines. Doesn't take much. And, I really don't know if you'd just want to add gin to a sauce without doing the above process that may prove a bit much.
I've also incorporated the use of beer in small quantities. One in particular is Mothership Wit beer as it has a high coriander flavor in it's profile.