Prepare the ingredients: Wash and dice the rhubarb. Finely chop the red onion, green bell pepper, and red bell pepper.
Combine in a pot: In a large, non-reactive pot, combine the diced rhubarb, chopped red onion, green bell pepper, and red bell pepper.
Add vinegar and sugars: Pour in the apple cider vinegar, granulated sugar, and brown sugar. Stir to combine.
Add spices: Add the mustard seeds, ground ginger, ground cinnamon, ground cloves, ground black pepper, and salt to the pot. Stir well to combine all the ingredients.
Cook the relish: Bring the mixture to a boil over medium-high heat. Once it reaches a boil, reduce the heat to medium-low and let it simmer, stirring occasionally, until the mixture thickens and the rhubarb is tender, about 30-40 minutes.
Adjust seasoning: Taste the relish and adjust seasoning if necessary, adding more salt or sugar to taste.
Cool and store: Remove the pot from heat and let the relish cool to room temperature. Transfer the cooled relish to sterilized jars and seal tightly. Store in the refrigerator for up to 3 weeks.
Serving Suggestions:
Serve the rhubarb relish as a condiment with grilled meats, such as pork or chicken.
Use it as a topping for burgers or sandwiches for an added tangy flavor.
Pair it with cheese and crackers for a delightful appetizer.
Enjoy this tangy and flavorful rhubarb relish as a versatile condiment for various dishes!