Preheat oven to 200C/fan 180C/gas 6. Put couscous in a heatproof bowl, then pour over 175ml/6fl oz boiling water. Cover and leave for 5 mins. Cut each tomato across about a third of the way down and scoop out the inside with a teaspoon, keeping the tomato intact. Place the tomato bits in a bowl. Scoop out the lid, discarding the core, then reserve the lid. Add garlic, paprika and couscous to the bowl of tomato bits. Leave for 1 min then mix with a fork.
Put the spring onions, coriander and mint in a bowl, then add the lemon juice, pine nuts, sultanas, olive oil and seasoning. Mix well. Add to the couscous and stir until combined.
Using a spoon, fill the tomato cases with the couscous mix. Top with the lids, place in a roasting tray, drizzle with a little olive oil and bake for 20 mins until soft.