Rinse and prepare all berries: hull strawberries and cut into quarters, pit cherries, leave raspberries and blueberries whole.

In a large saucepan, combine strawberries, cherries, raspberries, blueberries, and cranberries with 1/2 cup of water.

Add 1/2 cup sugar and lemon juice to the berry mixture. Stir gently to combine.

Bring the berry mixture to a gentle simmer over medium heat, stirring occasionally. Cook for 10-12 minutes until berries release their juices and begin to soften.

In a small bowl, mix 3 tablespoons of flour with 1/4 cup cold water to create a smooth slurry without lumps.

Slowly pour the flour slurry into the simmering berries while stirring constantly to prevent lumps from forming.

Continue to cook for 3-4 minutes, stirring gently, until the mixture thickens to a pudding-like consistency.

Remove from heat and stir in vanilla extract. Taste and adjust sweetness if needed.

Pour the Rote Grütze into individual serving glasses or a large serving bowl. Allow to cool to room temperature.

Cover with plastic wrap and refrigerate for at least 3 hours or overnight until completely chilled and set.

For the vanilla sauce: In a medium saucepan, heat milk and heavy cream over medium heat until steaming but not boiling.

In a bowl, whisk together egg yolks with remaining sugar until pale and creamy.

Slowly pour the hot milk mixture into the egg yolks while whisking constantly to temper the eggs.

Return the mixture to the saucepan and cook over low heat, stirring constantly, until the sauce thickens enough to coat the back of a spoon (about 5-7 minutes). Do not boil.

Remove from heat and stir in remaining vanilla extract. Strain through a fine-mesh sieve if desired.

Cool the vanilla sauce to room temperature, then refrigerate until ready to serve.

To serve, spoon the chilled Rote Grütze into dessert bowls and drizzle generously with cold vanilla sauce.