So if anyone is interested, here is a recipe I used. I didn't bother to weight caviar, but likely it was around 250g. Recipe was measured out for 500g.
1. To separate caviar from membranes take 500 ml of hot water (but cool enough that you can keep your hand in it for a while, if water is too hot, caviar will turn cloudy) with 1 tbsp of salt, put caviar into it for 5 minutes. Hot water and salt will make it easier to separate eggs from membranes.
2. Gently separate caviar from membranes, then wash it out under running water. It is better if colander isn't metal or covered in cheesecloth.
3. Make another batch of salt water, this time 3 tbsp for 500ml and room temperature, you can also add tea spoon of sugar to better preserve color and texture. Leave caviar in it for 15 minutes.
4. Pour out water, slightly dry caviar on paper towels.
5. Put caviar into serving saucer, add a little vegetable oil and mix. Ready to serve.
I am not sure how long it will keep, but I also doubt that it will become a problem.