Cut the bread in half, leaving the larger volume piece at the bottom to hold the filling. Remove part of the soft centre (la mie) to make room for the ingredients, leaving the crust and the bottom whole.
Rub the inside of the bread with garlic (to taste).
Cut the ripest tomato in half and salt it, so the juice starts to flow.
Soak both halves of the bread with the tomato juice, the vinegar, add the fine salt and then the pepper and olive oil.
Place the ingredients on the lower part of the bread: sliced tomato, thin slices of radish and chopped chives, sliced hard-boiled egg, chopped artichokes hearts, flaked tuna and/or anchovy fillets, chopped basil and olives.
Adjust the seasoning (salt, pepper and olive oil). Close the pan bagnat with the lid, pressing it down to pack the ingredients inside.
You can wrap the pan bagnat in cling film and chill it for at least an hour before serving. This is a juicy sandwich, don't forget to bring napkins to wipe up after eating.