Season the roe with the salt, pepper and lemon juice. Drain it in a sieve, and let it rest in the refrigerator for 30 minutes.
Melt all the butter in a small saucepan over medium heat. You will not be needing it all, but it is difficult to brown a smaller portion. Let the butter froth up, and stir while it slowly turns light brown and gives off a nutty aroma. Pour the clear butterfat from the burned whey.
Boil the potatoes in lightly salted water, drain well and let them cool.
Mash the potatoes and mix them with the other ingredients for the potato blinis. Season the batter with salt and pepper, and fry the flapjack-sized blinis with the browned butter for 1½-2 minutes on each side.
Serve the warm blinis with a good scoop of roe and a little dollop of skyr or yoghurt. Sprinkle the chopped red onion and the fresh herbs over them.