Steak Diane w/ Sautéed Potatoes & Peas

Ingredients

• four 5 to 7 oz tenderloin or sirloin steaks
• 1 lb small, waxy potatoes (Yukon Gold or any small, new potato)
• salt (1 tsp per L/qt of water)
• 3 shallots
• 4 oz cremini (or button) mushrooms
• 1 to 2 garlic cloves
• 1/3 cup brandy or cognac
• 1 tbsp Dijon mustard
• 1 tbsp Worcestershire sauce (or to taste)
• 1 cup heavy cream
• 1/3 cup flat-leaf parsley
• sea salt, to taste
• freshly ground black pepper. to taste
• 3 to 4 tbsp olive oil
• 1 tbsp unsalted butter
• 2 garlic cloves
• 3 small sprigs rosemary
• olive oil (for cooking)
• 1 tsp olive oil (if needed)
• fresh lemon juice (optional)
• unsalted butter (for finishing peas)
• 2 cups frozen peas
• freshly ground black pepper (to taste)