Step 1Fill a 4-quart pot about 3/4 full of cold water and add the salt. Turn the heat to high and bring the water to a boil. Turn the heat down to medium-high and slowly add the riso. Use a large spoon to stir it for a few seconds to make sure the pasta doesn't stick to the pot.
Step 2After 10 minutes, add the currants to the riso and stir again. With a small spoon, scoop up a few pieces of riso to test them for doneness. The pasta should be just tender, with no hard interior. When the riso is cooked, pour the contents of the pot into a colander with small holes or small mesh wire that you have placed in the sink. Shake the colander to get rid of any excess water.
Step 3Fill a large serving bowl with hot water and let it stand for a few minutes. Pour out the water, put the riso into the warm bowl, and taste the pasta again to see if it needs a bit more salt. If so, add salt, about 1/4 teaspoon at a time, stirring to mix well, until it suits your personal taste. Add pepper to taste as well. Add the mint and butter, stir to blend and serve hot.