My bro just reminded me that there are big differences between the 3 categories of restaurants which I use in my postings. I do agree with him but I guess I just assumed my visitors will be thorough enough in finding out more information before consuming food at any restaurants of their choice.
Anyway, I guess I better simplify the differences because some of my visitors might not even know what constitute as halal - I stumbled onto 1 forum where a muslim member defined halal as 'clean', as long long as the restaurant is clean, it is halal to her/him regardless whether pork is served or not. (the forum requires input from members on what halal means to them n they are required to put a note whether they are muslim or not). I'm not judging her/him but halal term is defined in Quran n Hadith - not a term that we can define as we please.
This site describe what is halal quite comprehensively http://www.crescentsofbrisbane.org/the_good_caterers_guide.htm read on to know more.
In Malaysia halal restaurant means the restaurant is issued with 'halal' certificate by a religious body (JAKIM) n as far as malaysian muslims are concern, even if the restaurant has no halal certificate but the operator is muslim and they don't serve alcohol, the restaurant is considered halal.
Well.. obviously the restaurant does not serve pork :-) however in multi racial country like Malaysia, the operator wishes to cater to the needs of non muslims too by serving alcohol on their premise; because of that JAKIM will not issue halal certificate to a restaurant that operates in this manner, even though halal meat is served (the operator procures meat for his restaurant from halal certified supplier).
The other category of pork-free restaurant is a premise that serves halal food (procures meat from halal certified supplier) but operated by non-muslims and the operator does not bother to apply for halal certificate from JAKIM.
Of course some pork-free restaurants do not use halal meat (slaughtered according to muslim law), but some muslims do eat at these places, but they will only consume meat-free and alcohol-free food - dishes like seafood, eggs etc.
All plant base food is halal (except those with intoxicating properties - marijuana etc or poisonous plants), however, not all vegetarian dishes are halal because some dishes use alcohol as flavour, additives etc; therefore should a muslim decides to eat at a vegetarian restaurant, do enquire on what ingredients are used for the dishes before ordering dinner :-)
Additional notes - just in case some visitors misunderstood that all animals' products are halal except pork as long as the animals are slaughtered n prepared according to Islamic law. Yeah - keyword MISUNDERSTOOD. Not all animals are halal even though they are slaughtered n prepared the Islamic way. Please refer to these sites for HALAL (lawful / permitted) n HARAM (forbidden) food: