Thoroughly rinse chicken livers, then marinate in salt, curing salt, nutmeg, and spirit for about 30 minutes. Do not rinse livers before using.
While the livers marinate, gently melt butter in a small saucepan. Bring half and half to a gentle simmer, remove from heat, add vegetables, and steep for 20 minutes. Strain liquid. Set aside.
Puree livers in a food processor until smooth, then add egg. Continue to puree in food processor and add in butter and cream, alternating between each to keep emulsified. Pour puree into large shallow container. Tap on solid surface to remove air bubbles, and let rest until the bubbles have settled.
Preheat oven to 225 degrees. In 4-ounce mason jars, portion 2 ounces of mousse. In a large pan, place filled mason jars, with lids on. Add water to base of pan, just enough to fill just up to the halfway edge of the mason jars. Cook covered for 1 hour or until internal temperature reaches 125 degrees.
Allow to sit at room temperature for about 30 minutes before transferring to refrigerator. Chill 1 hour, then top with sorghum gelee. Will keep for 4 to 5 days once gelee has been added.
Make the sorghum gelee
In a pot over medium heat, bring chicken stock to a simmer. Add leaf gelatin and continue to simmer until dissolved. Add the sorghum and vinegar and whisk to combine. Remove from heat and cool. Transfer to refrigerator and let cool until set.