Heat 60ml of olive oil in a saucepan and add the onions with a tsp sea salt and stir until onions start to cook down. Add the garlic, chilli and thyme leaves and cook on a low heat for 30 minutes. Allow to cool.
Place the flour and salt in a bowl. Add the olive oil and water and stir until the mixture becomes sticky dough. Turn out onto a well floured surface and knead for 3 minutes. Cover with plastic wrap and leave to rest for 45minutes at room temperature.
Preheat the oven to 220 degrees. On a piece of baking paper the same size as your baking tray (24x40cm) roll out the dough and turn in the edges 1cm to make a border. Spread the onions inside the border and scatter with tomatoes. Bake for 30 minutes then add the olives and place the anchovies creating a grid pattern on the pissaladiere. Bake for a further 10 minutes until golden.