In a bowl, mix olive oil, minced garlic, chopped rosemary, salt, and black pepper. Rub this mixture all over the lamb rack. Let it marinate for at least 1 hour at room temperature or overnight in the refrigerator.

Grill the Lamb

Preheat the grill to medium-high heat. Place the lamb rack on the grill, bone side down, and grill for about 15-20 minutes for medium-rare, turning occasionally. Let it rest for 10 minutes before slicing.

Prepare the Lamb Bacon Fingerling Potato Hash

Cook the Potatoes

In a skillet, heat olive oil over medium heat. Add the diced fingerling potatoes and cook until golden and tender, about 15 minutes. Stir occasionally.

Add Lamb Bacon and Vegetables

Add diced lamb bacon, onion, and bell pepper to the skillet. Cook until the vegetables are soft and the bacon is crispy, about 10 minutes. Season with salt, pepper, and stir in chopped parsley before serving.

Prepare the Sauce Béarnaise

Make the Reduction

In a small saucepan, combine white wine vinegar, shallots, and tarragon. Simmer until reduced to about 2 tablespoons. Strain and let cool.

Whisk the Egg Yolks

In a bowl, whisk the egg yolks with the cooled reduction until the mixture is thick and pale.

Emulsify the Sauce

Slowly drizzle in melted butter while whisking continuously until the sauce thickens. Season with salt and pepper to taste.