In a large bowl, combine the flour, yeast, salt and sugar. Add the olive oil and about 250ml warm (not hot) water. Either bring together by hand or with the dough hook attachment on a mixer.
Once it comes together, add up to 30ml more water – until it comes together into a (slightly sticky) ball. Knead for 8-10 minutes, then let rest in a lightly oiled bowl for 1 hour – 1h30m (until doubled in size).
While the dough rises, make the filling: add the drained sun-dried tomatoes to a food processor/blender (or use a pestle and mortar) and blend to a paste. Add the pesto and mix.
Once the dough has risen, punch down and put on a lightly floured surface. Roll to a rectangle about 40x30cm. Spread the sun-dried tomato/pesto mix to all edges and sprinkle over the cheese – press down to 'compact' the cheese a little.
Starting on the long side of the rectangle, roll the dough up tightly into a large roll. Use a knife/bench scraper to cut the roll in half (along the long part of the roll, as if the opposite of cinnamon rolls). Push the separated parts of the dough back so that the layers of pesto are face up.
Twist the two pieces of dough around each other, pinching each end to secure. This may be quite messy but just stick with it, it doesn't need to look perfect! Place onto a lined baking tray and let rest. (If making two loaves instead of one large, cut it in half at this stage).
Preheat the oven to 200C/180C Fan/Gas 6. Bake for about 30 minutes, until golden and the cheese is beginning to look a little crisp. Best served warm, but still wonderful once cooled!