Open Face Salmon Sandwich with Sweet Mustard Sauce

INGREDIENTS

• For the Sweet Mustard Sauce
• 2 tablespoons Dijon mustard
• 1 tablespoon honey
• 2 tablespoons olive oil
• 1/2 teaspoon lemon juice
• 1/4 teaspoon salt
• Freshly ground black pepper
• For the Sandwich
• 1 egg
• Four 4-ounce salmon fillets, about 1 inch
• thick, skin removed if desired
• 3 tablespoons olive oil, divided
• 2 tablespoons Sweet Mustard Sauce, (see above)
• Salt and freshly ground black pepper
• 1 tomato cut into four 1/2 -inch slices
• 1/4 red onion, sliced thinly
• 8 slices dark rye or multi-grain bread
• Mixed leafy greens
• 1 avocado halved, pitted, and cut into 1/2 inch slices
• 2 teaspoons capers, drained