Stir the flour, salt, and yeast in a large bowl.
Mix in the oil and 350ml water to form a soft dough.
Knead the dough on an oiled surface for 10 minutes until smooth.
Place dough in a bowl, cover, and let rise for 2 hours.
Preheat your oven to 220°C.
Clean the mussels, discarding any that do not close when tapped.
Heat oil and butter in a 23cm ovenproof pan.
Fry shallots, garlic, and fennel for 3 minutes until soft.
Add the carrot and tomatoes and cook for 1 minute.
Stir in the white wine and reduce the liquid by half.
Add the cream and simmer until reduced by half.
Stir in the herbs and mussels, then remove from heat.
Roll the dough into a circle slightly larger than the pan.
Cover the pan with the dough and tuck in the edges.
Brush the dough with egg yolks and bake for 20 minutes until golden.