and a beaver biryani for the wife

This came through the door while we were away earlier in the week. I promise you I have not digitally manipulated this image in any way - well, beyond a bit of cropping and resizing anyway.

Now the word "Tarka" may well have some meaning I'm not aware of - Google Translate offers no assistance in any of the obvious languages: Bengali, Gujarati, Hindi, Marathi, Urdu. Historically most Indian restaurants in the UK have been run by people from Sylhet, which is in what is now Bangladesh, and Google Translate doesn't specifically offer a Sylheti option, but it's apparently quite similar to Bengali, so it probably wouldn't have helped anyway.

If you're labouring through this in a fug of bafflement, let me help you out: the reason this is funny is that there is a well-known joke that goes as follows:

Waiter (imagine something a bit like this): And what can I get you sir?
Customer: I'd like a Chicken Tarka, please.
Waiter: Chicken.....Tarka?
Customer: Chicken Tarka.
Waiter: So.....Chicken Tarka.
Customer: Yes.
Waiter: So....Chicken Tarka. Chicken Tarka?
Customer: Chicken Tarka.
[Note that you can continue in this vein for as long as you think your audience will put up with it before proceeding to the punchline]
Waiter: So, just to recap: Chicken Tarka.
Customer: That's right.
Waiter: Are you sure you don't mean Chicken Tikka, sir?
Customer: Ah, no, you see, it's like Chicken Tikka, but it's a little otter.

Boom and indeed tish. There is even a recipe for Chicken Tarka online, which is doubly delicious, firstly because it all looks very nice, and secondly because the blog author seems to have missed the joke entirely. The answer to your next question is yes, they do appear to be American.

Just to spoil the joke a bit, it is of course true that there is a dish known as Tarka Dhal, and indeed it appears on the Tarka's menu just as it does on pretty much every other Indian restaurant's. This interesting Guardian article reckons that the "tarka" bit is "a mix of spices fried in oil or ghee until sizzling and aromatic". Which to be fair, sounds nicer than eating an otter anyway.