Chef John's Homemade Dijon Mustard

Combine white wine, water, vinegar, onion, and garlic in a saucepan; heat the mixture over high flame until it reaches boiling point, then lower the heat to a moderate level and let simmer for 15 minutes or until all flavors have melded together. Allow the mixture to cool down naturally and pour it into a large bowl through a fine-mesh sieve; discard the onion and garlic, and reserve the liquid for later use.

Add mustard seeds, dry mustard powder, garlic powder, and salt to the strained liquid; cover the bowl with a lid and let it sit at room temperature for 24 to 48 hours, allowing the mixture to thicken and develop its flavor.

Using a hand blender, blend the mustard mixture into your desired consistency. Transfer the blended mixture to a saucepan and add enough water to achieve a smooth texture; bring the mustard mixture to a gentle simmer, then lower the heat to a moderate level and cook, stirring constantly, until all flavors have combined.

Fill hot, sterilized jars with the mustard mixture and leave about 1/4 inch of space at the top. Use a knife or thin spatula to remove any air bubbles from the jars after they have been filled. Wipe the rims of the jars with a damp cloth to remove any food residue. Close the jars by screwing on the lids and tightening the rings.

Refrigerate the mustard for at least 1 week, allowing all flavors to blend together and mature.