Preheat oven to 425 degrees. Place pork on a baking sheet, and bake in preheated oven for 30 - 40 minutes, until internal temperature reaches 150 degrees. Once cooked, cut into 1/4" slices.

Meanwhile in a small pot, bring water, vinegar, sugar, and salt to boil. Add sliced jalapenos, and gently boil for 4 - 5 minutes. Remove from heat.

Toast rolls, and add a thin layer of mustard. Top with sliced pork, jalapenos, and swiss cheese.