Place the cherries in a saucepan, pour in enough water to cover the berries. Put the saucepan on the fire. When the water boils, add sugar and stir. Reduce the heat to low and cook the berries for 10 minutes.
Strain the resulting compote through a fine sieve.
Dissolve the starch in a cup of water and pour it into the cherry compote. Put the compote on the fire and cook for 2 minutes until it thickens slightly. Then remove from the fire, let the jelly stand and thicken.