Remove kidneys from the packaging and pat dry with kitchen
paper, then slice in half removing any white core that's
Toss in the flour and season well with salt and pepper.
Melt the butter in a large non-stick frying pan. Add the onion
and sugar then sweat gently for 3-4 minutes, or until soft, sweet
Shake off any excess flour from the kidneys and add them to the
pan. Cook them with the onion over a medium-high heat for 2-3
minutes, turning every now and then.
Add the vinegar, tomato purée and mustard to the pan, then
gradually add 250ml of light chicken stock or water, stirring
constantly. Bring to the boil; add the lea & perins sauce to
the pan and season with salt and freshly ground black pepper.
Reduce the heat and simmer gently for 15 minutes, or until the
kidneys are tender and the sauce is thickened, stirring
While the kidneys are cooking, grill the pancetta until nice
and crisp then toast the bread and spread with butter and put on
four warm plates. Spoon the kidneys and sauce over the buttered
toast and scatter with chopped chives, finish wish crispy pancetta.
Serve immediately while piping hot.