Chilled wintermelon and shrimp soup

These days, the house generally looks like a warzone because of the packing, and I am not in the mood for involved cooking. So I'm making very simple bentos, and mostly one-dish/one-pot type of things for dinner. A great one-pot meal is soup of course, but it is also summer, when we aren't always in the mood for a steaming hot bowlful.

The answer is chilled soup that can be made ahead and just taken out at dinnertime. This one is really easy to make too, which is a big plus. Winter melon has a inherently cooling quality according to old (Chinese) medicine, so this is really nice to have on a warm evening.

A bit about wintermelon

The name wintermelon (in Japanese tougan 冬瓜) is a little misleading, because it may seem that it's a melon that is only in season in winter. It actually ripens in hot weather in temperate zones (it can be grown year round in hotter areas), but the hard, waxy outer skin allows it to be kept in a cool place for a long time, so that it can be eaten in the winter months. I think it's most suitable for eating in the warm months, because it's watery and very subtle in flavor, with a crisp texture that is retained even after cooking (though cooking it for a very long time will make it soft).

Winter melon has a pale green, shiny smooth skin, and is quite big. (Be sure it's smooth skinned - the dark green crinkly ones you may see sold nearby are bitter melon (also called goya, in Japanese nigauri にが瓜) and are treated quite differently.) You see them anywhere from around 10-15 cm / 4-6 inches in diameter on up. If you buy a whole one, you can keep it in a cool cellar until you decide to use it. You can also buy cut portions, which may be a more convenient for a small family or if you don't want to commit to one huge fruit.

When you cut into it, it looks like this.

The inner part with the seeds is fluffy and inedible (like the innards of a pumpkin, to which it is related), so you need to scoop it out. The skin is really quite tough, so be careful when peeling it.

In Japanese cooking, winter melon is usually cut into bite size squares and parboiled for about 10 minutes in plain water, before being stewed, used in soups, stir-fried, and so on.

Recipe: Chilled wintermelon and shrimp soup

• 2 cups of parboiled wintermelon cubes
• 5 cups dashi stock, vegan dashi stock or chicken stock (yes you can use water and granules or a stock cube - I do myself when I'm in a hurry)
• 1 Tbs. soy sauce
• 1 Tbs. mirin or sherry
• 1 Tbs. kurosu (black vinegar) or balsamic vinegar
• 1 tsp. fresh ginger juice (grate some fresh ginger and squeeze out the juice)
• 200 g / about 7 oz. fresh shrimp, shelled and deveined
• Salt
• Green garnish (here I have used edamame and green onion tops from the garden)

If you haven't already, peel, de-seed and cut up the wintermelon into cubes about 1 inch / 2 cm big. Put them in a pot of water, bring up to a boil and cook for about 10 minutes. Drain.

Put the wintermelon in a pot with the dashi, soy sauce and mirin. Bring up to a boil, then simmer slowly for about 15 minutes.

In the meantime, peel and devein the shrimp, and cup up into chunks (or use small shrimp). Add the shrimp to the soup. Simmer a couple of minutes, and add the ginger juice and vinegar. Taste and add salt if necessary.

Take the pot off the heat, and transfer the contents to a bowl or other refrigerator-appropriate container. Let cool down to room temperature cover tightly with plastic film or a lid and chill until ice cold. (You can put it in the freezer for about 30 minutes before serving to make sure it's really cold.)

Serve garnished with some edamame, green onions, etc. on top.

The soup keeps in the refrigerator for a couple of days. To make it a complete one-bowl meal, add some cooked and well rinsed somen or soba noodles, a bit more soy sauce, and a lot of green onions on top.

Vegan version

Use a vegetable stock or vegan dashi stock, and blanched (boiling water poured over and drained) tofu cubes instead of the shrimp. You may need to add a bit more soy sauce to compensate for the blandness of the tofu.

Other variations

• Try cut up chicken breast instead of the shrimp
• Add some cut up tomatoes and a bit more vinegar
• Scoop out the wintermelon and shrimp, thicken about 1 cup of the soup with 1-2 Tbs. cornstarch, and pour over as a sauce. This is called ankake.
• Gelify the soup with gelatin or agar-agar for an interesting savory jelly