798 calories is more than a plate of char kway teow, and it is sold as breakfast. The rice cubes are not the problem. 200g of lontong is about 260 calories, similar to a scoop of rice. The sayur lodeh is. It is vegetables cooked in thick coconut milk, and a 250ml ladle is about 260 calories with almost all of it from coconut fat. The egg is 75, the tempeh or tau kwa about 100 because it is fried, the sambal 40, and the serunding on top another 60.
The hawker stalls that sell lontong usually sell mee soto next to it. Mee soto is about 433. Same counter, same S$4, and one bowl is nearly double the other. The difference is entirely the coconut gravy versus the clear turmeric broth. If you want the Malay breakfast and you are counting, mee soto is the easier choice by about 365 calories.
Lontong goreng, the fried version with the rice cubes tossed with sambal and vegetables, is around 550 because there is no coconut gravy, but it does take on frying oil. If you want the rice cakes and the sambal without the lodeh, that is the middle option.