Preheat oven to 350 degrees.
Dice potatoes and toss in a baking dish with olive oil, salt and pepper. Roast fr 30-40 minutes, until tender and brown. Set Aside.
Meanwhile, place salmon on a sheet pan covered in aluminum or parchment paper. Blot the salmon with a paper towel to get off any excess moisture. Drizzle with olive oil and salt and pepper. When potatoes are done place salmon in the oven and roast about 10-12 minutes, depending on thickness, until is flakes easily with a fork.
In a bowl mix together the mayo, lemon juice, dill, 1/2 tsp kosher salt and pepper. If your dressing is too thick, use a little more lemon juice to thin it out. You can even use water, or white vinegar. 1 tsp at a time.
Chop your romain lettuce up and divide equally among four plates. You can use as much or little romaine lettuce as you want. I typically like about 2 C per plate.
Dice your cucumber and divide it amount the four plates along with the roasted potatoes.
Using a fork, break the salmon up and divide it among the four plates as well. Drizzle the dressing over each salad. Serve warm, or at room temperature.