1. Add the lukewarm water and the yeast to a large bowl, and combine well.
2. Add the flour, sugar (if using) and salt to the bowl, and carefully bring together. Mix for 10 minutes to develop gluten. At the start it will be a sticky, wet dough but work until it starts to come together and there is no flour sticking to the edge of the bowl. Alternatively you can mix it in a stand mixer with the dough hook.
3. Grease a tin with 1 tbsp of olive oil and add the dough. Cover with a towel and leave in a warm spot to proof until it doubles in size. This should take an hour or two. You could use your air fryer on the reheat setting at 49°C for 45 minutes to do this step too!
4. Once the dough has doubled in size, sprinkle over your sliced veg along with the 4 tbsp of olive oil to the dough, and a generous pinch of salt on top of the proven dough. Dimple the focaccia until you have created thick indents in the dough and the veg is now sticking to the dough.
5. Cover again with a towel again and leave to proof for a second time again. You want to proof it until it has doubled in size compared to the original dough.
6. Bake at 170°C for 15 minutes.
7. Once baked, spoon the pesto on top and bake for a further 5 minutes at 170°C. Take out and leave to cool.