Heat the oven. Preheat oven to 400°F. Brush a large, rimmed baking sheet with avocado oil.
Boil the potatoes. Scrub potatoes and place them in a medium saucepan. Cover them with water and bring boil. Simmer for 15 minutes. Drain and dry potatoes.
Make the parmesan mixture. Mix the salt and parmesan cheese in a small bowl. Add 1 tablespoon of the minced sage and set aside.
Cook the pancetta. While potatoes are boiling, heat a small non-stick skillet over medium heat. Add pancetta and cook for 5-6 minutes until lightly browned and crisp. Remove the pancetta from the pan with a slotted spoon and drain on a plate lined with paper towels.
Smash the potatoes. Place dry potatoes on the prepared rimmed baking sheet. Using a meat tenderizer, or another heavy flat object, gently smash potatoes, trying to keep them in one piece as much as possible. Drizzle or spray with olive oil, making sure to get some oil on each potato
Roast the potatoes. Bake for 15 minutes. After 15 minutes, add the parmesan mixture and cooked pancetta to the potatoes, carefully tossing to coat. Return potatoes to oven and cook and additional 15 minutes, until crisp and golden brown on the edges.
Make the sauce. While the potatoes are baking, melt 1 tablespoon of butter in a small non-stick saucepan over medium heat. Add shallots and sauté for 2 minutes. Add flour and cook for an additional 30 seconds. Add wine, cream, broth and lemon juice. Cook for 4 minutes, stirring constantly. Add remaining tablespoon of butter and cook untifor about 1 minute, until the butter is melted. Remove from heat and stir in sage, pepper and salt.
Serve. Drizzle cooked potatoes with sage sauce and serve immediately.