FINELY CHOP enough sage leaves to measure 1/3 cup and set aside.
COARSELY CHOP remaining sage leaves and stems to measure 1/2 cup and place in a small stainless steel saucepan with white wine. Bring to a boil over medium heat, stirring and pressing sage to release flavor. Remove from heat. Cover tightly and let steep for 5 minutes.
TRANSFER sage infusion to a sieve placed over a glass or stainless steel bowl and press leaves with the back of a spoon to extract all the liquid. Discard solids and return liquid to saucepan. Add mustard seeds. Cover and let stand at room temperature until seeds have absorbed most of the moisture, about 2 hours.
PREPARE boiling water canner. Heat jars and lids in simmering water until ready for use. Do not boil. Set bands aside.
COMBINE marinated mustard seeds (with liquid) and vinegar in a blender or food processor fitted with a metal blade. Process until blended and most seeds are well chopped, but retaining a slightly grainy texture.
TRANSFER mixture to a stainless steel saucepan and add lemon zest, lemon juice, honey, salt and reserved finely chopped sage. Bring to a boil over high heat, stirring constantly. Reduce heat to low and boil gently, stirring frequently, until volume is reduced by a third, about 20 minutes.
LADLE hot mustard into hot jars leaving 1/2 inch headspace. Remove air bubbles. Wipe rim. Center lid on jar. Apply band until fit is fingertip tight.
PROCESS jars in a boiling water canner for 10 minutes, adjusting for altitude. Remove jars and cool. Check lids for seal after 24 hours. Lid should not flex up and down when center is pressed.