Step 1

Prepare your canner, jars and lids. Wash your jars and bands in hot, soapy water, rinse and bring to a simmer in your water bath canner to sterilize. Always use new lids for safe preserving.

Step 2

Combine rhubarb, brown sugar, raisins, onion, vinegar, salt and spices in a large, stainless steel pot and bring to a boil on high heat, stirring frequently. Reduce heat to medium/medium-high and boil gently, stirring frequently until ingredients break down and form into a thick sauce.

Step 3

Use an immersion blender to blend sauce until smooth (or omit this part if you don't mind a few chunks of rhubarb and raisins in your sauce).

Step 4

Ladle into hot Mason jars leaving ½-inch headspace at the top. Slide a knife around the inner "edge" of the jar to remove any air bubbles. Adjust headspace as needed. Wipe rims, place lids on top and screw bands on.

Step 5

Place jars in canner and bring water to a boil. Process in a boiling water bath for 15 minutes, then turn heat off, remove lid and let cool in your canner for another 5 minutes. Remove jars and allow to cool completely before storing.