Warm a sauté pan over a moderate heat. Scatter the caster sugar and melt for a minute until just starting to colour. Toss the cherries in the pan with orange zest and lemon juice and lavender if using.
Tilt the pan onto one side and carefully pour the kirsch over the cherries, let the kirsch ignite. Once the flame has extinguished, continue to cook for a further minute or until the cherries are starting to break down. Remove from the heat.
Spoon the cherries and juices into serving dishes and add some ice cream.
Enjoy straight away.