Heat oil in a medium saucepan and over medium heat until shimmering. Add the garlic and anchovy paste and cook, stirring frequently, until fragrant, about 30 seconds. Add the remaining ingredients and bring to a boil. Cover, reduce heat to medium-low, and simmer for 30 minutes. Remove from heat and pour liquid through a fine mesh strainer set over a large bowl. Transfer to several small air-tight container (I use canning jars) and cool to room temperature. Transfer to the refrigerator if you plan to use within a few days; otherwise, store in the freezer for up to 6 months.
I call for anchovy paste only because that is what I had on hand. You can substitute a couple minced whole anchovies or leave them out all together if you prefer.