Prepare the focaccia dough, kneading the sage in as you work. Set aside to rise (about 1 1/2 hours).

Preheat the oven to 450°F/220°C/gas 7. Oil a baking sheet.

Roll the dough out into a rectangle about 10 x 15 inches (25 x 38 cm) and place on the baking sheet.

Dimple the surface with your fingertips. Brush with the oil and sprinkle with sea salt.

Bake for 30 minutes, or until golden. Serve hot or at room temperature.