Prepare canner, jars & lids.
Combine wine, vinegar, onion and garlic in a medium saucepan. Bring to a boil over high heat, then reduce heat and simmer for 5 minutes. Remove from heat and allow aromatics to steep in the wine for 10 – 15 minutes.
Strain vegetables from the infused wine, pressing on solids to release all the juice. Return wine to the saucepan and add salt, honey and Tabasco, if using. Over medium heat, whisk in the mustard powder; continue whisking and heating until the mustard comes to a boil. Stirring constantly, boil mustard until it reduces to your desired thickness, remembering that it will thicken further upon cooling (I cooked mine for about 10 minutes). Taste and adjust seasonings.
Fill hot jars to a generous 1/4-inch headspace (more like 1/2-inch), tamping down the mustard into the jar. Thoroughly bubble by passing the handle of a wooden spoon along the edges and middle of the jar. Wipe rims, affix lids and process in a boiling water bath for 10 minutes. Allow to rest for 5 minutes in the hot water prior to removing from the canner.