Combine the sugar, lemon zest and lemon juice in a small saucepan and cook over very low heat for 10 minutes, until the sugar is dissolved. Add the strawberries and continue to cook over very low heat for 20 minutes, until the strawberries release some of their juices and the mixture boils slowly.
Prepare churros as instructed on the package. Drain on kitchen towel.
Serve each portion of churros with sauce and white chocolate shreds on the top.