2 tablespoons Dijon mustard
1 tablespoon honey
3 tablespoons olive oil, plus more for brushing salmon and bread
2 limes
Kosher salt and freshly ground black pepper to taste
1 pound salmon fillets
1 red onion, sliced into half moons
1 tomato, cut into 1/2 inch thick wedges
4 thick slices rye or multigrain bread, brushed with olive oil
4 leaves romaine lettuce or a handful of smaller greens
1 egg, hard boiled and sliced
1 avocado, cut into slices
1 1/2 teaspoons capers