Beer Baked Scalloped Potatoes

Bahan-bahan (6 porsi)

• 1 teaspoon vegetable or canola oil
• 1½ cups sliced onion
• 1 cup beer
• 2 pounds medium red potatoes, (peeled and cut into ⅛-inch slices)
• ½ teaspoon salt, (divided)
• ¼ teaspoon freshly ground black pepper, (divided)
• 2 tablespoons all purpose flour
• ½ cup nonfat milk
• ½ cup grated Swiss cheese