Does the word 肉 always mean pork (unless preceded by another word which means a different animal) in Chinese menus?
I worked in restaurants for many years. As I understand it, '肉' in Chinese menus only refers to pork unless it is specifically stated what kind of meat it is.

For example:


時菜炒（豬）肉片 = in-season vegetable stir-fry pork slice
時菜炒牛肉 = in-season vegetable stir-fry beef
（豬）肉絲湯麵 = shredded pork noodle soup
雞絲湯麵 = shredded chicken meat noodle soup


(豬) is omitted most of the time because when no specific is given, it is the default meat.

But there are always exceptions:


Since the most common meat you see in 夹馍 are 羊肉 (mutton) or 牛肉 (beef), even when people reduce 羊肉夹馍 or 牛肉夹馍 to '肉夹馍', '肉' still refers to mutton or beef
If it is 清真食物 (Halal food) menus, you can be sure 肉 on the menus are not pork but mutton or beef instead


Outside of menus, 肉 can refer to any kind of meat, for example: 肉 in "大魚大肉" or "有酒有肉" does not refer to a specific meat.