Niçoise focaccia sandwiches

Tip the yeast and sugar into a large bowl with 500ml warm water and 1 tbsp of the oil. Whisk to combine and set aside for 5 mins until frothy and bubbly. Mix in the flour and 2 tsp fine sea salt until you have an even, sticky dough. Transfer to an oiled bowl, cover and leave to prove for 3-5 hrs in a warm spot until doubled in size and bubbly, or chill for up to 24 hrs.

Oil a 20 x 30cm tin and line with baking parchment. Drizzle ½ tbsp of the oil over the baking parchment. Lightly oil your hands to ensure the dough doesn’t stick to them and scoop it up from one side, stretching it out and tucking it back underneath the rest. Turn the bowl by a quarter and repeat. Repeat this process two more times, then tip the dough out into the prepared tin. Gently stretch the dough out to help ease it into the corners of the tin, then set aside. Cover with a clean tea towel and leave to prove in a warm place for 2-4 hrs until doubled in size, very jiggly and bubbly.

Meanwhile, tip the sliced potatoes into a pan of cold water. Bring to the boil, then reduce the heat and simmer for 2-3 mins until almost tender. Drain well, then leave to steam-dry. For the salad, peel the garlic and use a pestle and mortar to crush it to a paste along with the anchovies, if using, and a pinch of salt. Mix in the vinegar, mustard and reserved olive oil from the cans of tuna (about 4 tbsp). Season to taste and set aside. Cook the eggs in a pan of simmering water for 8 mins until just hard-boiled, adding the green beans for the final 3 mins. Drain well, and immediately plunge both into a bowl of cold water to cool.

Heat the oven to 220C/200C fan/gas 6. Drizzle the remaining 1 tbsp oil over the focaccia dough and press your fingers all over the surface to make dimples. Scatter over the cooked potatoes and olives, and drizzle over a little more oil. Sprinkle over 2 tsp sea salt flakes. Bake for 25-30 mins until the focaccia is golden and the base sounds hollow when tapped. Transfer to a wire rack to cool completely.

Peel and slice the eggs. Once the focaccia has cooled, halve it through the equator. Gently toss the tuna in the dressing along with the green beans, onions, tomatoes and lettuce leaves until well combined. Spoon the salad over the base of the focaccia, then scatter over the sliced eggs and sandwich with the top of the focaccia. Cut into squares to serve.