Place the flour, polenta, yeast and salt in a bowl and mix together. Add the measurement water, 3 tablespoons of the oil, the cumin seeds and chilli and mix together to form a dough. Knead the dough in an electric mixer for 5 minutes, or by hand on a lightly floured surface for 10 minutes, until the dough is soft and springy. Place in a lightly oiled bowl, cover with clingfilm and leave in a warm place for about 1 hour until the mixture has doubled in size.
Tip the dough out on to a lightly floured surface, then punch it down and knead a couple of times until the air is knocked out. Divide the mixture into 8 equalsized balls and keep loosely covered with lightly oiled clingfilm. Roll out each ball until 5 mm (¼ inch) thick.
Heat a griddle pan until smoking hot. Brush over the flatbreads with a little oil, then cook, in batches, for 3–5 minutes on each side until lightly charred and cooked through. Tear into large chunks and serve warm, scattered with a little chopped red chilli, some cumin seeds and sea salt flakes, if liked.