Chinese Sweet & Sour Tofu Stir-Fry with Snow Peas

One to three days before cooking, drain and rinse tofu. Wrap in foil and freeze until solid, at least 3 1/2 to 4 hours. One day before cooking, place the tofu in a bowl and transfer to the refrigerator to thaw overnight.

Place the thawed tofu on a plate lined with a double layer of paper towels. Cover with another 2 paper towels, place a plate on top and set a weight, such as 2 cans of beans, on the plate. Let stand for 20 minutes.

Combine pineapple juice, ketchup, and soy sauce in a small bowl; set aside.

Cut the pressed tofu into 12 slices, a scant 1/2 inch thick. Lightly dust both sides with cornstarch.

Heat a 12-inch stainless steel skillet (or 14-inch flat-bottomed carbon-steel wok; see Tip) over high heat until a drop of water vaporizes within 1 to 2 seconds of contact. Swirl in oil, reduce heat to medium, and add the tofu in an even layer. Cook until light golden on the bottom, about 1 minute. Turn over, sprinkle with ginger, and cook until the second side is light golden, 1 minute more.

Remove from heat. Add snow peas and the reserved sauce. Cover and let stand until the sauce stops sputtering, about 30 seconds. Uncover, return the pan to medium heat, and stir-fry until the sauce is well distributed and the peas are tender-crisp, 1 to 2 minutes. Sprinkle with scallions.