INGREDIENTS
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1 recipe Basic Burger
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2 tablespoons olive oil
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1 large onion, thinly sliced
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2 10-oz. packages button mushrooms, thinly sliced
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Salt and pepper
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2 tablespoons chopped fresh parsley
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2 teaspoons lemon juice
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1/2 teaspoon chopped fresh thyme
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8 ounces Swiss cheese, cut into 8 slices
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Asian Mayo
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Pesto Mayo
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Spicy Ketchup
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Ranch Olé
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The Baconator