This is not identical to the Russian dish of the same name, but it's a close recreation that's both tasty and easy.
*note... I used a baking stone because this salmon dish was always served on a hot stone in the restaurants we visited, and it does seem to make a difference in how well everything bakes. But I'm certain this recipe would work with a regular baking dish or jelly roll pan (that's a cookie sheet with sides, just to be clear).
What you need:
Large salmon fillet
Potatoes Au Gratin, boxed instant (I think we used "Idahoan")
---ingredients necessary for boxed potatoes (typically water, milk, butter)
Fresh dill, chopped
How to do it:
1. With a baking stone already in oven, preheat oven according to box instructions. Our box indicated 450°.
2. As oven heats, prepare potatoes. When ready, grease stone with light spray of olive oil. Rinse salmon, place on stone and lightly spray salmon with olive oil. Place potato dish on middle rack and salmon stone on rack directly under potatoes.
3. Bake 20 minutes or as indicated by box instructions.
4. When potatoes are finished (ours had five additional minutes after sprinkling parmesan), remove from oven along with salmon stone. Pat up any excess oil from stone with paper towel if necessary. Spoon potatoes onto salmon and garnish with tomatoes and dill. Serve.