For the herb oil: Warm the olive oil, add the chopped basil leaves and chilli flakes. Allow them to steep in warm oil for at least 30 minutes or overnight.
For the focaccia dough: In a small bowl, mix the warm water and sugar together. Add yeast and allow it to activate. Let it rest for 10 minutes or till the mixture becomes frothy and bubbly.
In the meanwhile, place 2 cups of flour, salt and oil in a large bowl. Mix this with the help of a wooden spoon. Now add half of the yeast solution and mix well.
Add another 1 cup of flour and remaining yeast solution, continue to mix it well. Add the last cup of flour and stir till the dough starts coming together.
Turn over the bowl and drop the dough on a lightly oiled work surface and knead it till the dough is smooth, elastic, soft and slightly sticky.
Place the dough in a well oiled bowl and cover it with a kitchen towel. Allow it rise and leave it for 90 minutes till it doubles in size.
Place the risen dough on a work surface and punch it down to flatten. Divide the dough into two portions to make 2 large focaccia loaves.
Place one portion of the flattened dough on a greased rectangular pan. If need be, then flatten it a bit more. Now pour 1/4th of the prepared herb oil on the dough. Using your finger tips, dimple or indent the dough about 2 inches apart. Cover it.
10 minutes before baking, preheat the oven to 200 degrees celsius. Once the dough is ready, pour another 1/4th portion of herb oil onto the risen dough. You may need to lightly dimple again. Sprinkle coarse salt if you like.
Bake for 30 minutes or till the bread turns golden brown in colour. Remove from the pan and allow it to cool slightly. Serve warm with the same herb oil if you like. Repeat the same process for the second loaf.