Bitter gourds that are really bitter have hard, narrow ridges and are darker green. The less bitter ones are relatively softer, less green, more yellow, and have wide ridges. The bitter gourds I cook are the big ones that, over the years, have become less bitter. I used to sweat them before cooking but that's not necessary now.
I love frying the living daylights out of thinly sliced bitter gourd. The wok must be stonking hot and no water is added so that everything is dry and nicely charred. That includes an egg which, because there's too little oil, sticks to the wok and burns. I then scrape it up with a spatula, making sure I get everything off. These little bits of slightly burnt eggs, along with the garlic and caramelized light soya sauce, add to the fragrance from the charred bitter gourd.
Dry-fried bitter gourd may look quite unattractive compared to a green and moist stir-fry that has water added. But the strong aroma more than makes up for the lack of looks. I'd rather enjoy bitter gourd with my mouth and nose than eyes. The proof of the pudding is in the eating!