Place ingredients in a mason jar or glass bottle. Cover tightly and gently shake a few times. Store in a cool, dark place and shake the jar daily. Taste each day until infusion reaches desired intensity, 7 to 10 days. (If the infusion is too intense, you can dilute it to taste with the plain spirit.) Strain through a fine-mesh strainer or paper coffee filter into another clean, airtight glass jar or bottle, and store in the refrigerator.