Mix the sugar with the salt and spread over the pigeon breasts. Place in a non-metallic bowl, cover loosely and leave to marinate in the refrigerator for 2–3 hours.
Wipe off the salt and sugar and pat the pigeon breasts dry with kitchen paper. Melt the butter in a large heavy-based frying pan and fry the pigeon breasts for 5 minutes until lightly browned on both sides. Drain to a plate and set aside.
Add the onion and bacon to the pan and fry gently for about 5 minutes until the bacon is beginning to crisp.
Stir in the tomatoes, vinegar, stock and spelt and bring to the boil. Reduce the heat, cover and cook gently for 25 minutes or until the spelt is just tender.
Cut the pigeon into slices, add to the pan with the basil and a little salt and pepper and heat through. Serve scattered with extra basil.