Pour the milk over the oats in a mixing bowl, stir and leave to soak until softened.
Season with salt, Provençal herbs and paprika, then add the eggs and whisk until smooth.
Fold in the chopped green onion, drained flaked tuna and shredded mozzarella until evenly combined.
Heat a little oil in a non‑stick pan over medium heat.
Pour the mixture into the pan, spread it evenly and sprinkle sesame seeds on top.
Cook until the underside is golden and the edges are set, then carefully flip.
Cook the other side until crisp and fully set.
Let the skillet rest briefly, then cut into slices and serve warm.