To make the brine, put first seven ingredients in a saucepan with three cups water; bring to a boil, whisking to dissolve sugar and salt, reduce heat and simmer for about five minutes. Cool completely, stirring occasionally, then pat chops dry and put them in a Ziploc bag with the brine. Seal and place in a bowl in the icebox for at least four hours and up to overnight, flipping at least once.
To make marmalade, juice two Satsumas, removing seeds. Zest the other four Satsumas, then peel and cut the flesh into small pieces, removing seeds and reserving juice. Place juice, zest, pieces, sugar, onion, tomotoes, vinegar, ginger and 1 cup water in a saucepan. Bring to a boil, stirring to dissolve sugar, then simmer over low heat, stirring occasionally, for 30-45 minutes. When thick and almost syrupy, stir in horseradish to taste, then add ketchup and adjust salt to taste.
When ready to serve, remove chops from the brine and pat dry. Let sit 20 minutes, then season with salt and pepper and sear, grill or broil for five-six minutes per side, or until they register 140 degrees at their thickest spot. Serve hot with marmalade on the side.