Peel the onion and finely chop it. Peel the garlic cloves and crush or finely chop. Halve the pepper and scrape out the seeds and membrane. Cut the flesh into 1cm strips. Chop the tomatoes roughly into small pieces.
Pour 1 tbsp oil into a pan and warm up over a medium-high heat for 2 mins. Add the lamb to the pan and cook for 2-3 mins, turning once or twice, till browned on all sides. Scoop out the lamb and transfer to a plate. Reduce the heat under the pan to medium.
Slide the chopped onion and pepper to the pan and cook for 6-8 mins, stirring every now and then, till softened. Add the garlic and cook for a further 1 min.
Drain the cannellini beans and rinse well. Add them to the pan along with the tomatoes and 400ml boiling water. Crumble in the stock cube and stir well to combine. Return the lamb to the pan. Bring the water to the boil, then reduce to a simmer. Pop a lid on the pan and cook for 30 mins.
Meanwhile, pour the bulgar wheat into a bowl and sprinkle in a pinch of salt. Top up with 300ml boiling water, and cover the bowl with a large plate. Set aside to soak for 15 mins. When ready, fluff up with a fork and squeeze in the lemon juice. Pour in 1 tbsp oil and stir well.
Finely chop the parsley. When the stew has cooked and the lamb is tender, stir through the parsley. Have a taste of the sauce and add a little more salt and pepper if needed. Pile the bulgar wheat onto plates and top with generous ladles of the lamb stew and serve.