Kielbasa Hash without eggs

2 -3 tablespoons oil 1 1/2-2 onions , sliced thinly 3 medium potatoes , cut in half lengthwise, then sliced thinly 1 -2 red bell pepper , sliced 6 garlic[...]

1 tablespoon unsalted butter 1 tablespoon grapeseed oil 1/8 teaspoon fresh ground black pepper 24 ounces sweet potatoes , finely diced (skin-on, about 1 large[...]