Combine yeast, sugar and 60mL of the water in a small bowl. Set aside in a warm place for 10 minutes or until foamy.
Combine the flour and salt in a large bowl, and make a well in the centre. Add the yeast mixture and remaining water and use your hands to bring the dough together. Turn onto a clean work surface. Knead for 10 minutes or until dough is smooth and elastic. Brush a large bowl with a little of the oil. Add the dough. Cover with a tea towel. Set aside in a warm draught-free place to prove for 1 hour or until doubled in size.
Lightly grease a large baking tray with some more of the olive oil. Gently place the dough onto the tray and push into an oval. Cover and set aside to prove for 45 minutes or until risen slightly.
Gently fold the dough into thirds and turn upside down, pressing into a slightly larger oval. FirmLy press the quartered beetroot into the bread. Cover and set aside to prove for 30 minutes.
Preheat oven to 250°C/230°C fan forced. Place a deep tray of water in the base of the oven. Drizzle remaining oil over the bread and sprinkle with sea salt flakes. Bake on the highest shelf for 20 minutes or until bread is golden. Set aside to cool.
Meanwhile, stir the juice, vinegar and caster sugar in a small saucepan over low heat for 5 minutes or until the sugar dissolves. Bring to the boil and simmer rapidly for 5-6 minutes or until thick and syrupy. Stir in the lemon juice.
Sprinkle salt, goat's cheese, micro beetroot leaves and walnuts over the focaccia. Drizzle the syrup over the focaccia.