Chef John's Dijon Mustard | Sauces & Dips | Umami

Ingredients

• 1 ½ cups white wine
• 1 cup water, or more as needed
• ⅔ cup white wine vinegar
• 1 yellow onion, chopped
• 2 cloves garlic, minced
• 1 cup whole yellow mustard seeds
• ¼ cup dry mustard
• 1 tablespoon garlic powder
• 1 teaspoon salt
• 4 1-pint canning jars with lids and rings