Taken from The Red Spoon
Ingredients:4 large russet baking potatoes, scrubbed (about 3/4 pound each)
6 tablespoons light mayonnaise
2 tablespoons plus 1 teaspoon water, divided
1.5 teaspoons tomato paste
1 teaspoon anchovy paste
4 tablespoons Dijon mustard, divided
1/2 medium white onion, finely chopped
2 tablespoons olive oil, plus additional for coating potatoes
1 slice firm white bread
2 tablespoons milk
1/2 pound bulk breakfast chicken sausage
1 tablespoon chopped basil
1 cup Parmesan cheese, shredded
Prick potatoes with a fork. Microwave, covered with a paper towel, on high power until tender, 10 to 12 minutes.
Cutting lengthwise, divide in half and scoop out centers, leaving a 1/4-inch to 1/2-inch thick walls.
Whisk together mayonnaise, 2 tablespoons water, tomato paste, anchovy paste and 3 tablespoons mustard.
Preheat oven to 350°F with rack in middle.
Cook onion in oil with a pinch of salt in a small heavy skillet over medium heat, stirring occasionally until golden, about 10 minutes.
Meanwhile, tear bread into small pieces, then soak in milk in a medium bowl until very soft. Mix in sausage, basil, onion and 4 tablespoons mayonnaise, and Parmesan cheese mixture with your hands.
Divide filling between potatoes, then coat skins lightly with oil. Bake in a 4-sided sheet pan until sausage is cooked through, about 30 minutes.
While potatoes bake, whisk 2 tablespoons mayonnaise mixture with lemon juice, remaining teaspoons mustard and 1 teaspoon water, and salt and pepper to taste.
Remove potatoes from oven and turn on broiler. Spoon remaining mayonnaise mixture over filling and broil 3 to 4 inches from heat until charred in spots, 3 to 5 minutes. Cool slightly.