2 tablespoons black mustard seeds
1 medium onion, chopped
1/2 cup white wine vinegar
1/4 cup water
1/2 cup coconut milk
2 tablespoons butter, optional
2 tablespoons whole-grain mustard (I used a raspberry whole-grain mustard that I’m trying to finish up, hence the pinkness)
Salt and freshly ground black pepper
3 pounds green beans, trimmed
Bring pot of water to boil. When boiling, add green beans and cook 5-8 minutes or until crisp-tender. Drain and shock in bowl of cold water to stop the cooking. Drain again.
While boiling water, toast mustard seeds in dry skillet over medium heat, about 30 minutes or until they start popping. Remove to a plate and set aside.
Add onion, vinegar, water and coconut milk to skillet and bring to a boil. When boiling, lower heat to a simmer and cook until thickened, about 10 minutes. Remove from heat and stir in butter if using, mustard seeds, and mustard. Season to taste with salt and pepper.
Toss green beans with coconut-mustard sauce, adjusting seasoning if necessary.