Dietary challenges
The choices we make with our diet can be important to us for health, ethical or cultural reasons. If you have special dietary requirements or allergies then it can be essential to know what ingredients have been used in or around your food. For example, if you have nut allergies or are lactose intolerant you need to be assured that your meal is free of these items. If you follow a vegetarian, vegan or kosher diet then you want to know that your meal is free of meat or cooked according to your requirements. Even if you only have a strong dislike to a particular food, you should feel free to ask if that ingredient is in your meal.
Speak to the chef
As the customer, it is always permissible to enquire regarding the ingredients in your meal. Indeed, for the reasons listed above, your restaurant is obliged to answer your questions regarding your meal and how it has been prepared. Their menu may explain what is in their food, or a polite request to speak to the chef about your requirements should be granted. Bear in mind that a chef in a busy restaurant is catering to all patrons and may pass the information back to you via his waitstaff.
Contact your restaurant or café beforehand if you need to request a specially prepared meal or to check that they will have menu choices to suit your requirements.