Fry the onion in the olive oil in a thick based pot or pan over a low heat, stirring regularly, until soft but not brown, 8-10 minutes.
Add garlic and pul biber. Continue frying for another 1-2 minutes, then add the chopped tomatoes. Mix and leave to simmer until the tomatoes have released their liquid and most of this liquid has evaporated, around 10 minutes. Season with salt and pepper. Take off the heat.
Simultaneously, boil the orzo pasta in plenty of salted water until al dente. You can also use other small pasta or even spaghetti broken into small chunks. Drain and mix into the ready tomato sauce.
Make the feta yoghurt by whisking together the yoghurt and finely crumbled feta cheese with a fork. Season with black pepper.
Mix the cherry tomatoes and torn basil leaves into the tomato sauce and pasta. Serve immediately, topping with the feta yoghurt and a good glug of extra virgin olive oil.
