Step 1In a small saucepan, bring the water and black beans to a boil over high heat. Lower the heat to simmer and cook for 20 minutes. Strain and use immediately or partially cover, cool and refrigerate for up to several days. This makes about 3 cups of stock, more than is needed for the remainder of the recipe; the stock will keep, covered and refrigerated, up to 1 week.
Step 1Cut the tofu into chunky matchboxes, each about 1 1/2 inches by 2 inches by 1/2 inch. Line a plate with a dish towel or double layer of paper towels, then place the tofu on top to drain for 5 to 10 minutes.
Step 2Meanwhile, in a bowl, combine the one-fourth teaspoon salt, soy sauce and black bean stock to make the seasoning liquid. Taste and season with additional salt if desired. Set this seasoning liquid with the other ingredients near the stove.
Step 3Heat the oil in a large nonstick skillet over high heat. Blot dry the tofu, then pan-fry until golden brown and lightly crisp, 3 to 4 minutes per side. Transfer to a plate, leaving the oil behind.
Step 4Reduce the heat slightly and add the chile and garlic. Cook, stirring constantly, until fragrant, about 15 seconds. Scatter in the mushrooms along with 1 to 2 pinches of salt. Give things a turn, then splash in the rice wine and stir. After the wine evaporates, add the black beans. Continue to cook until the mushrooms have softened slightly, about 1 minute, stirring constantly.
Step 5Return the tofu to the skillet, gently toss to combine, then pour over the seasoning liquid. Reduce the heat to a gentle simmer and cook for 2 to 3 minutes, turning over the tofu midway. When about half of the liquid has been absorbed, stir in the cornstarch slurry. Cook, gently stirring, until the sauce thickens slightly and clings to the tofu, about 1 minute. Stir in the green onion and continue to cook just until the onion starts to wilt. Remove from heat, stir in the sesame and chile oils and transfer to a plate.