Remove and discard the ends of the bitter melons. Halve lengthwise, and scoop out seeds and pith with a small metal spoon and discard. Slice crosswise into 1/4” (6 mm) half-moon pieces.
Bring a small pot of water to a boil. Add the bitter melon slices. Let cook for 30 seconds or so, until half-cooked. Drain the bitter melon with a colander and set aside.
Heat oil in a large nonstick pan (or a wok) over medium-high heat until hot. Add the dried chili pepper (if using), garlic, and fermented black beans, stir a few times until fragrant. Add the blanched bitter melon slices and stir for 1 minute or so. Add soy sauce and sugar. Stir until the bitter melon is just tender, 1 minute or so. Taste the bitter melon. Sprinkle with more salt and stir again, if needed. Once done, transfer everything to a plate.