Bring the goat milk, salt and honey to a simmer in a sauce pot just long enough to melt the honey. Transfer the mixture to an ice cream machine and process until the sorbet has thickened and increased in volume, about 45 minutes per batch depending on your machine. Transfer the sorbet to a container and freeze until needed. To serve the sorbet, place some custard dishes in the freezer to chill. Remove the custard dishes when it's time to serve and drizzle two tablespoons of syrup in each. Top the syrup with a few scoops of sorbet, garish with the black walnuts and yarrow, and serve immediately.
I'm including syrup recipes for both red and black currants. You wouldn't think that there would be much difference, but black currants are usually bigger than red or white currants from my experience, and the extra flesh means they yield about twice as much finished syrup.