Finely chop enough sage leaves to measure 1/3 cup. Set aside.
Coarsely chop remaining sage leaves and stems to measure 1/2 cup and place in a small 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 nd let stand at room temperature until seeds absorb most of the moisture, about 2 hours.
In a blender or food processor combine marinated mustard seeds (with the liquid) and vinegar. Process until blended and most of the seeds are well chopped. (You want to retain a slightly grainy texture).
Transfer mixture to a stainless steel saucepan and add the 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 prepared jars leaving a 1/4" headspace. Check for air bubbles and adjust headspace if needed.
Process in a boiling water bath for 10 minutes. Adjust time according to altitude.