* - cooked until crisp, drained, and crumbled.
Trim off and discard tough stems and bruised spinach leaves. Drain, wrap in damp paper toweling, and refrigerate until ready to use, at least several hours. When ready to use, spinach will be dry and crisp.
Trim and slice mushrooms diagonally. Place in nonmetal bowl, add lemon juice, and toss to blend. Cover and refrigerate until ready to use.
Combine remaining ingredients except crumbled bacon. Beat until blended. Refrigerate until ready to use.
Beat dressing just before using.
To serve, combine spinach leaves, mushrooms, and dressing, add crumbled bacon, and serve at once.