Prepare the Kidneys:

Rinse the beef kidneys under cold water and trim any excess fat.

Soak the kidneys in milk for 30 minutes to 1 hour to reduce any strong odors and enhance tenderness.

After soaking, drain and pat them dry with paper towels. Cut the kidneys into bite-sized pieces.

Sauté Aromatics:

In a large skillet, melt the butter over medium heat.

Add the chopped shallots and minced garlic; sauté until translucent and fragrant, about 2–3 minutes.

Cook the Kidneys:

Increase the heat to medium-high and add the kidney pieces to the skillet.

Cook, stirring occasionally, until browned on all sides and cooked through, approximately 8–10 minutes.

Deglaze and Simmer:

If using white wine, pour it into the skillet to deglaze, scraping up any browned bits from the bottom. Let it simmer for 2–3 minutes to reduce slightly.

Stir in the Dijon mustard, ensuring the kidney pieces are well-coated.

Reduce the heat to medium and pour in the heavy cream. Stir to combine, allowing the sauce to thicken slightly, about 3–5 minutes.

Season and Serve:

Season with salt and freshly ground black pepper to taste.

Garnish with chopped fresh parsley.

Serve hot, accompanied by crusty bread or over a bed of mashed potatoes.