- 1 tablespoon high-heat oil
- 1 red onion, chopped
- 3 cloves garlic, chopped
- 1 tablespoon yellow mustard seeds
- 1/3 cup red wine vinegar
- 1/3 cup currants
- 1/2 cup brown sugar
- 1 pound rhubarb, trimmed and sliced
- Salt and pepper, to taste
Heat oil in a saucepan over medium heat. Cook onions until soft, about 5 minutes. Stir in garlic and mustard seeds and cook an additional 2 minutes. Carefully add vinegar and currants; bring to a simmer. Add sugar and stir until dissolved.
Stir in half the rhubarb and bring to a boil. Reduce heat and simmer, partially covered, until rhubarb breaks down, about 10 minutes. Stir in remaining rhubarb and bring back to a boil. Reduce heat to a simmer and cook just until rhubarb is tender, about 2 minutes. Season to taste with salt and pepper; add more vinegar or sugar, as necessary.
Cool completely and store in the refrigerator for up to 1 week.