3 tablespoons olive oil, separated
1 1/2 pounds Yukon gold potatoes (about 4 medium), washed and unpeeled
1 teaspoon kosher salt, separated
1/4 teaspoon ground black pepper, separated
5 tablespoons balsamic vinegar
2 teaspoons Dijon mustard
1 tablespoon fresh rosemary, chopped
1 teaspoon whole grain mustard
1 clove garlic, peeled and crushed
1/2 red bell pepper, thinly sliced
1/2 yellow bell pepper, thinly sliced
1/2 orange bell pepper, thinly sliced
1/2 white onion, thinly sliced
1 (14-ounce) package kielbasa (or Polish sausage), sliced into thin rounds about 1/4-inch thick