Asparagus with Garlic Mustard Sauce

Bahan-bahan (4 porsi)

• 1 pound asparagus, (trimmed)
• ¼ cup (½ stick) butter
• 2 cups sliced fresh mushrooms
• 2 tablespoons country-style Dijon mustard
• ½ teaspoon minced fresh garlic
• ¼ teaspoon freshly ground black pepper
• ⅛ teaspoon salt