Put the warm water in a jug, add the yeast and mix briefly. Leave for 5 minutes or until frothy.

Put the flours, sugar and salt in a large mixing bowl and make a well in the centre. Pour in the yeast mixture and combine with your hands until everything just comes together. Add the olive oil and mix well to form a loose dough.

Turn the dough out onto a work surface and knead for about 8 minutes using the ‘slap and fold’ technique.

Lightly oil a large clean bowl, then add the dough and cover with lightly oiled cling film. Leave in a warm place for 1-2 hours until doubled in size.

Heat the oven to 160°C/140°C fan/gas 3. Put the spring onions in a small baking tray, drizzle over the balsamic vinegar, then sprinkle over the sugar and a pinch of salt. Toss to coat, then bake for 6-8 minutes until soft. Set aside.

When the dough has risen, turn it out onto a work surface and knead gently for 5 seconds to distribute the air. Carefully lift the dough into a 20cm x 30cm high-sided rectangular baking tin.

Arrange the spring onions on top and dot with the rosemary sprigs. Sprinkle generously with sea salt flakes and drizzle with oil. Create dimples all over the surface of the dough by pressing deep down with your fingertips, then leave it to prove in a warm place for at least an hour or until nearly doubled in size.

Heat the oven to 220°C/200°C fan/gas 7. Bake the focaccia for 10-15 minutes until golden, then lower the heat to 200°C/180°C fan/gas 6 and cook for 20 minutes more.

Take the focaccia out of the oven and drizzle with more oil, then leave it to sit in the tin for 5 minutes. Carefully remove the bread from the tin, then cut or tear it into thick slices and serve warm.