Rinse the sushi rice with cold water and drain in a colander.

Place the rinsed rice in a pan and add the boiling water.

Let the water evaporate slightly, then cover the pan and cook over low heat for about 5 minutes. Ensure the rice does not stick to the bottom of the pan.

Allow the cooked rice to cool completely.

Poke small holes in the sausage.

Place the sausage in a non-stick pan and cook until browned on both sides.

Turn off the heat and let the sausage cool.

Line a bowl with plastic wrap.

Mix the black sesame seeds and white sesame seeds together in a shallow dish.

Place some rice on the plastic wrap.

Top the rice with some cooked sausage.

Add more rice on top of the sausage.

Twist the plastic wrap as if wrapping a piece of candy, taking care to release the air.

Unroll the plastic wrap and roll the rice ball in the sesame seeds.

Repeat the process until all the rice and sausage are used.

Grate the tomato, taking care not to grate the peel.

Drizzle the grated tomato with olive oil and balsamic vinegar.

Season with salt and freshly ground pepper.

Serve the rice balls with the tomato sauce.