Char siew is that sweet, glossy red BBQ pork you see hanging in the Chinese roast meat shop window. 100g at around 290 calories is honestly not bad for a roast meat, and the 24g of protein is genuinely good. But two things are working against you bro. First, char siew is usually cut from pork shoulder or belly, which carries a fair bit of fat, so even before any sauce you are starting fattier than chicken. Second, that beautiful red lacquered glaze is basically a sugar bomb of honey, maltose, sugar and soy painted on layer by layer. That is where most of the 14g of carbs come from. The caramelised burnt edges everyone fights over taste incredible and are pure sugar.
Cut choice is the biggest lever. Lean char siew can drop the fat noticeably, while the fatty belly version with the white streaks can push 100g toward 340 calories. The other trap is portion. A char siew rice plate gives you way more than 100g, often 150 to 200g, so just doubling the meat alone can be 500 plus calories before the rice. If you are at the roast shop, ask for lean over fatty, eat it with rice and veg rather than stacking it with siu yoke, and you have got a reasonable high-protein meal.