Pro tip #1: Although there may be no "Halal" certificate, you can opt for "Vegan Friendly" restaurant to get a dish made from halal ingredients. The same goes for groceries. search for "Vegan" label on the product that you buy.
Pro tip #2: For most students, the food portion here is particularly large (2-3 portions of regular Indonesian food). be sure to have a plan if you can't finish your food in one sitting (ask for takeaway or bring empty lunchbox)