Although there are different ways to batter and deep-fry food, in order to make the batter stick, a lot of places rely on eggs (via Healthline). While there are alternatives to eggs, like aquafaba and yogurt, per Vegan Food & Living, it doesn’t mean that restaurants are necessarily using these options when deep-frying food.
With this in mind, if you’re not at a vegan restaurant and you’re ordering, say, tempura or another type of deep-fried vegetable, you definitely want to inquire about its vegan status. Although someone who is new to veganism may not be able to taste the difference, because veganism is about being ethical in how you eat and respecting the life of animals, just the fact that you could possibly be consuming an animal product is enough to question the preparation of the food. Some restaurants can accommodate the dietary needs of vegans, while others can’t. So it’s important to be mindful of this.