Dry fry the millet in a large frying pan for 3 to 4 minutes until golden and releasing a smoky aroma, then transfer to a saucepan, Add the stock, bring to the boil, cover and simmer gently for about 20 to 25 minutes until the grains are swollen and the stock is absorbed. Transfer to a large bowl.
Meanwhile, grill the peppers under a high heat for 15 to 20 minutes turning them over as one side chars until charred all over. Put in a bowl, cover and leave until cool enough to handle, Remove the pepper skins, core and seed over a bowl to catch the juice. Slice the pepper flesh into short strips.
Heat 1 tbsp olive oil in a frying pan. Add the onion, garlic, chilli and mixed spice and fry gently for 5 minutes. Mix in the diced tomatoes and remove from heat.
Whisk the remaining oil with the balsamic vinegar and reserved pepper juices. Add to the cooked millet with the spiced tomato mixture, pepper strips and basil. Mix well and season with salt and pepper to taste. Serve warm.