Divide the salmon among 4 serving plates, and squeeze a little lemon juice over the top.
To make the dressing, combine the olive oil, vinegar, mustard, and honey in a small bowl. Whisk together until well combined, then season with salt and pepper.
Sprinkle in half of the dill, and whisk again. Taste, and adjust the seasonings as needed. Toss the cucumber with the remaining dill, then spoon the cucumber onto the plates. When ready to serve, drizzle with the dressing, and serve with the sliced bread.