Heat the oil in a 24cm round ovenproof dish on the hob over a medium/high heat and add the sausage pieces. Cook for 4-5 minutes until browned all over, then remove from the pan. Add the onion and fennel to the pan and cook for 5 minutes, until softened and lightly golden.
Add the garlic and peppers and cook for 1 minute, then add the tomato purée, tinned tomatoes, thyme and oregano with a splash of water. Return the sausages to the pan and add the olives. Simmer everything together for 10 minutes, then remove from the heat.
Meanwhile, halve the cucumber and scoop out the seeds, then cut into half moons. Roughly chop the vine tomatoes, then mix with the cucumber and mint. Dress with the lemon juice and season.
Lay the halloumi pieces out over the top of the dish then place under a hot grill. Cook for 3-4 minutes, until the halloumi is deep golden and everything is bubbling. Leave to cool slightly for a few minutes, then garnish with the torn basil leaves and serve with the salad.