Vegan and Vegetarian food is almost always Halal, however there are a few exceptions, including some small unexpected ingredients that can make foods Haram.
So while not all Vegan and Vegetarian food is Halal, the vast majority is. The only potentially non-Halal Vegan food is Alcohol and things that may have it, such as Vanilla extract, which contains a very small amount of alcohol.
Many claim Vanilla Extract is indeed Halal despite containing a small amount of Alcohol, however it’s up to your interpretation of Islamic Law.
What about Vegetarian Food?
While everything vegan is Halal except for Alcohol and Alcohol-containing products such as Vanilla Extract, Vegetarian food isn’t quite as simple.
Again, it’s up for interpretation to some extent, as I would (as would many others) consider the vast majority of Diary-Milk to be Non-Halal as in the end the slaughter/death of the animal is typically against Islamic-Law and isn’t Halal. The same applies to Eggs, dairy-cheese, etc. Not to even mention many Cows/Chickens are fed “Pork” in their feeds, which in my opinion would make their milk Non-Halal.
But the bottom line is not all Vegetarian food is Halal, even if you do not agree with the above interpretation that I believe in. This is because Whey is Non-Halal and is in many vegetarian foods, such as protein powders, dairy ice-cream, and even breads.
While Whey is not a concern if something is Vegan, as vegans do not eat dairy and thus wouldn’t have it, it is a concern if you eat vegetarian food. Whey isn’t Halal.
Are Meat-Replacements Halal?
As far as I’ve seen there are no non-Halal Vegan meat replacements, so just make sure it does not contain whey or eggs (and thus is vegan and not vegetarian) and it should be 100% Halal. Alcohol isn’t used in Meat replacements, so the only concern should be whey.
That means if you want one of those vegan sausages or hotdogs made by lightlife, Field Roast, Tofurky, or Beyond Meat’s Vegan Sausages go right ahead. They’re all 100% Halal.
Or if you simply wanted a vegan/vegetarian non-meat “meat”-type food that’s Halal, most of Quorn’s products are Halal (Check for whey if it’s not vegan), all of Gardeins are Vegan, and I believe most of Morningstar’s meat-replacements are vegan (Check for whey, as it’s non-halal and sometimes in theirs).