Preheat the oven to 200°C (392°F). Place the schnitzels on a baking sheet lined with parchment paper and bake for 10 minutes, or fry them in a deep pan for 3 minutes.

Chop the lettuce into thick pieces.
Slice the cucumber into rounds.
Cut the tomato into rounds.

For the Ketchup Sauce:
In a bowl, mix the ketchup and mayonnaise with the paprika until well combined.

For Assembling the Baguette:
Cut the baguette in half. Spread the ketchup sauce on the bottom, then layer the lettuce, tomato, cucumber, and finally the schnitzels.