In Norway the traditional summer dish on the south coast is fried mackerel --- with rhubarb soup on the side! Sounds like a weird combination maybe, but it's really good.
1/2 kg. rhubarb, diced
1 liter water
2 - 3 tablespoons sugar
2 tablespoons potato starch (the most common thickener in Norway, use Maizena or some such)
Boil the water, add the rhubarb and sugar. Simmer until the rhubarb is tender. Dissolve the thickener in a little cold water, add slowly to the soup while stirring. Bring to a boil then remove from heat. THE SOUP IS SERVED LUKEWARM OR COLD as an accompaniment to fried mackerel and maybe potatoes but no other veg.
But our killer rhubarb recipe is a cake or crumble, served hot from the baking dish with whipped cream or vanilla ice cream. On the rare occasions there is any left over, it never lasts more than 24 hours in the fridge.