Sambal Udang is actually one of the better lauk options at the nasi campur counter, bro. A full hawker plate sits around 300 calories, which sounds okay until you realise that most of those calories, about 160 of them, come from the cooking oil alone. The prawns are 115 kcal, the sambal paste is only 20 kcal. So the dish itself is not the problem; it's the wok technique and how heavy-handed the cook is with the oil. To be honest, these are ballpark estimates because there's basically no solid published calorie data for Malaysian hawker sambal udang. Different cooks, different oil amounts, different prawn sizes. Take the 300 figure as a reasonable middle ground, not a hard measurement.
The thing that really changes the maths is portion size and how much gravy you take. A small nasi campur scoop can be as low as 190 calories if you get a lighter ladle. Ask the aunty for 'kurang kuah' and you drop maybe 40 to 60 kcal straight away. On the other end, if you go butter prawn or cereal prawn, you're looking at 420 calories because those are deep-fried in batter with a butter-egg coating. Udang goreng tepung is even worse at 480 calories due to the batter absorbing oil. Stick to sambal and you keep the protein-to-calorie ratio decent, 22g protein at 300 kcal is genuinely not bad for a lauk.