Make the dressing: Put the oil, vinegar, honey, mustard, egg, 1/2 teaspoon salt and 1/4 teaspoon pepper in a blender and blend until smooth. Stir in the poppy seeds. Refrigerate until ready to serve.
Make the salad: Put the strawberries in a nonreactive heatproof bowl. In a small saucepan over medium heat, combine the vinegar, 1/2 cup water, the bay leaf, sugar, 1 teaspoon salt and 1/4 teaspoon pepper. Bring to a low boil and allow the sugar to dissolve. Pour over the strawberries and let stand about 20 minutes. Remove the bay leaf and drain the strawberries, discarding the liquid.
In a large salad bowl, combine the spinach, red onion, mushrooms and pickled strawberries. Pour the dressing over the salad, toss well and serve immediately.
Photograph by Con Poulos
Courtesy of Food Network Magazine