Sausage, Pepper, and Potato Bake

Ingredients

• 3 tablespoons olive oil, separated
• 1 1/2 pounds Yukon gold potatoes, 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 package kielbasa, sliced into thin rounds about 1/4-inch thick

Directions

1. Heat the oven to 400 degrees F. Slick a 9x13 baking dish with 1 tablespoon of olive oil, using your hand or a brush to coat the base and the sides; the oil helps the potatoes brown against the dish. Slice the potatoes thinly, about 1/8-inch thick, using a mandoline if you like. As you cut, try to keep the slices grouped together so they are easier to arrange.
2. Set the potato slices into the dish in 4 slightly fanned rows, overlapping them at an angle. Sprinkle them with 1/2 teaspoon kosher salt and 1/8 teaspoon black pepper.
3. Bake the potatoes for 30 minutes. Meanwhile, make the vinaigrette: add 2 tablespoons olive oil, the vinegar, Dijon mustard, whole grain mustard, rosemary, garlic, and the rest of the kosher salt and black pepper to a glass jar with a snug lid, or place them in a bowl.
4. Close the jar and shake it hard until everything is blended. If you are using a bowl, whisk the mixture or blend it with an immersion blender. Set it aside.
5. Carefully take the dish of potatoes out of the oven. Spread the peppers over the potatoes, add the onions on top, and finish with an even layer of sausage.
6. Shake the vinaigrette hard again, then pour it evenly over the casserole.
7. Return the dish to the oven and bake for 30 minutes more, until a knife slides through the center of a potato without resistance.
8. Remove the dish from the oven and let it cool for 5 minutes before serving. Leftovers can be stored in a covered container in the fridge for up to 2 days.