In a small bowl whisk the mustard powder,
sugar, wine, vinegar, salt and turmeric until
smooth and thick. Adjust the consistency with
up to 1 teaspoon warm water. It should be
thick, but not pasty since it will tighten up a
bit as it sits. Chill for at least one hour or
up to 3 days to allow the flavors to meld. It
should be very sharp and a bit sweet.
Preheat the oven to 300 degrees F.
Put the bread in the oven to warm while cooking
the franks. Heat a large griddle or nonstick
skillet over medium heat and add the butter.
When melted, add the franks and cook, turning,
until hot through and browned on the outside,
about 5 minutes.
To assemble, put a frank inside a warm piece of
bread and drizzle with the sweet hot mustard to
taste. Top with sauerkraut.