Start by preparing the dough. Mix the flour, sugar, salt and yeast in a bowl. Add in the warm water and olive oil, then knead until smooth. Cover and let rise for 1 hour
Sauté the onions in the olive oil with the balsamic vinegar and brown sugar until deeply caramelised, about 30–40 minutes. Set aside
Roll the dough into a 30 x 30 cm rectangle, spread the caramelised onions across the dough, then sprinkle with the thyme leaves
Roll the dough up into a long, skinny log, slice down the middle into two skinner logs, then twist the two lengths together. Tuck the ends underneath
Place the loaf in a greased and lined loaf tin, then cover and let rise for another 30 minutes
Preheat the oven to 180°C
Bake for 25–30 minutes until golden. Let cool before slicing
