In a bowl, combine flour, yeast, salt, sugar, and olive oil. Add water gradually until a smooth dough forms. Place in a sealable bowl and let rise for 1 hour in a warm place. The dough is ready when it shows fine bubbles throughout and rolls out easily.
While the dough rises, prepare the sauce and season to taste. Preheat oven to 210°C (410°F). Oil a baking sheet and roll out the dough on it. Spread the sauce evenly on the dough, covering the base completely.
Distribute blanched vegetables over the sauce. Layer salmon, tuna, and crab on top. Sprinkle with cheese. Bake for 15 minutes at 210°C (410°F) until the cheese is completely melted and lightly browned.