Michelin Starred Restaurants and Butter

Hi all, I have a friend who has lactose intolerance and I’m looking for nice, Michelin-starred or Michelin Guide restaurants that can cater to my friend’s dietary preference - which includes not being able to eat butter.

Now, I’m a big foodie and I love eating out. I dine at Michelin-starred restaurants a few times a year and a lot of the dishes seem to have loads of butter on them.

A few questions:

1. Would Michelin-starred restaurants be able to produce quality dishes substituting butter and dairy items in tasting menus?
2. Would this limit us to specific types of cuisine that don’t often use butter? Like heading to Thai or Japanese tasting menus as opposed to French/European tasting menus?

If you’re based in London, it would be great if you could also recommend great restaurants that could cater to this sort of dietary preference (butter substitutes).

Thanks all.