In a bowl, combine and stir the mustard and fig jam. Set aside.
Spread the insides of the Kaiser buns with butter and fig. Top the bun bases with the goat cheese, fig slices and capicollo.
In another bowl, toss the arugula with the lemon juice and olive oil. Add salt and pepper, and mix. Top the sandwiches with arugula and close them. Serve immediately.
TIPS
If fresh figs are unavailable, pear slices can be used instead.