Place the lentils, sage and one garlic clove into a pan and cover with water.
Bring to a boil, then reduce the heat and simmer for 30 minutes until the lentils are tender. Drain and return to the pan.
Season to taste with salt and freshly ground black pepper, a squeeze of lemon juice and the olive oil. Keep warm until needed.
For the chard, bring another pan of salted water to the boil. Add the chard and cook for 1-2 minutes until tender. Drain and set aside.
Heat a frying pan until hot and add the olive oil, garlic and chilli and the chard. Stir-fry for one minute.
For the liver, heat a large frying pan, add the butter, pancetta and sage and cook for two minutes until crispy.
Add the liver and cook for a further one minute on each side. Remove from the pan and place on serving plates.
To make the balsamic sauce, drain off any excess fat in the frying pan and return to the heat. Add the balsamic vinegar and crème fraîche and cook for one minute, whisking to combine.
To serve, add the braised chard to the plates, then top each plate with a spoonful of lentils.
Spoon over the balsamic sauce.
