In a large saucepan, heat grapeseed oil and red pepper flakes over medium oil until warm.
Add the grated onion. Cook over medium for approximately 5 minutes until onion becomes translucent but does not begin to brown. Add the minced garlic and cook for one more minute.
Remove the pan from heat. This is especially important if you are using a gas cooktop. Once removed from the heat, add the bourbon.
Return to heat and bring mixture up to a simmer. Cook for 5 minutes to allow bourbon to reduce.
Next add all remaining ingredients. Whisk or stir to combine well. Cook on low/medium-low for 20 to 30 minutes until sauce has reduced to the thickness you prefer in a BBQ sauce. I cook mine for 30 minutes, however some have preferred this sauce to be cooked as little as 15 minutes for a thinner sauce.
Allow to cool and store in jars. This sauce should be kept refrigerated.