Season the veal kidneys generously with coarse salt and freshly milled pepper. Place them in a copper sauté pan (ideal for even heat) and cook in the oven at 180°C (thermostat 6/7) for 30 minutes on each side.
Remove from the oven, deglaze and degrease the pan. Return the kidneys to the pan, add the crushed juniper berries.
Pour in the gin and flambé. Add the veal jus and lemon juice, reducing until nearly dry. Off the heat, whisk in the butter for a silky sauce. Set aside.
Deglaze the kidneys once more, then slice into 1 cm thick pieces.
Arrange the slices on plates, coat gently with the sauce, and garnish with finely chopped flat-leaf parsley.
Serve alongside creamy gratin dauphinois for a classic French pairing.
