Cook the mixed grain rice. Feel free to cook it as you would normally cook white rice. Since you're making sushi, reduce the water a little to make the rice a bit firmer.

Cut the cucumber into thin semi-circles and rub with salt. When tender, rinse well and drain. Cut the salmon slices in half.

Combine the ingredients marked with (A) to make the sushi vinegar. Fold the vinegar into the cooked rice, and when cooled, mix in the cucumber.

Split the rice into 20 equal portions and shape into balls. Place a piece of salmon on top of each followed by a little dill to decorate.