Heat a skillet over medium heat. Add the sardines, sliced tomatoes, and red onion. Sauté for 2-3 minutes, until warmed through and slightly caramelized.
Squeeze the juice of ½ lemon over the sardines and vegetables.
Layer the lettuce on the toasted bread, followed by the sautéed sardines, tomatoes, and onions.
Serve immediately and enjoy.
Notes
No Sardines: Use smoked salmon or canned tuna– substituting sardines with tuna will reduce the omega-3 and vitamin D content.
