It’s very important to not overcook the tofu. If it’s overcooked, the tofu will be tough to chew and won’t taste good at all, especially as cold leftovers. Some people prefer to leave the sauce thin so it can be mixed into their rice bowl, so feel free to reduce the sauce in step 4 to your desired thickness.
Whisk water, corn syrup, maesil cheong, soy sauce, fish sauce, sesame oil, garlic, and gochugaru together in bowl. Stir in Fresno chile, jalapeño, yellow onion, and half of green onion. Set sauce aside.
Rinse tofu and pat dry with paper towels. Halve tofu block lengthwise, then cut crosswise into ½-inch slices. Arrange tofu in single layer on paper towel–lined plate. Pat tops dry with additional paper towels, then sprinkle with pinch of salt.
Heat neutral oil in 12-inch nonstick skillet over medium-high heat until shimmering. Arrange tofu salted side down in skillet. Sprinkle with remaining pinch of salt and cook until light golden brown, 3 to 5 minutes per side.
Add sauce and cook, constantly spooning sauce over tofu, until sauce has thickened and begins to coat tofu, about 2 minutes. Remove skillet from heat and sprinkle with remaining chopped green onion and pepper. Serve. (Refrigerate for up to 1 week.)
