Several recent-ish (South Asian) customers...

...at the one (Thai) restaurant where I work now:

1) A (late middle age) (very pleasant) (upscale) (South Asian from South Asia) woman took charge of ordering for her large family group of like five or six people and everything goes very smoothly, but then like fifteen minutes after her order, she calls me over to the table and says that instead of having the one dish be vegetable, please have it be tofu, because they don't have tofu in any dish that they ordered, and they should have one dish with tofu.

So, I'm like, "I'm sorry, ma'am, I can go check, but I think it's probably too late for that now because your dish is probably already cooking," and I offer the option of ordering a side of fried tofu if that's the case, to which she assents, and I go back and check, and their dish is one minute from coming out, and so I place the side-order of tofu, which is very unusual and which the (Thai) (husband) owner immediately notices when it prints out and so calls me over and asks what's up, and so I tell him it's "an Indian table" and they wanted to change a dish to tofu fifteen minutes after ordering when it was already coming out of the kitchen, and so they ordered that side dish instead, so they could have some tofu with their meal.

And, he didn't say much, and just went back to cooking.

2) A(n early 50s) (South Asian from South Asia) man had ordered like ten minutes earlier, and he suddenly shows up at the back counter and starts demanding no fish sauce, no oyster sauce, and he says he has an allergy and so to make sure no fish sauce, no oyster sauce, and so I'm like, "I'm sorry sir, I'll go back and check, but is this a dietary preference, or is this an allergy?", and he keeps saying allergy, but my sense is that it isn't, it's just him making that up in order to get what he wants when he wants, and I don't like that behavior one single bit, it's highly manipulative, and so I press him on the nature of the allergy, and he can't say, and even though he speaks (English) at an extremely high level, he just goes back to saying no fish sauce, no oyster sauce, he has an allergy, and by that point like two minutes have gone by, and then suddenly my one (older) (Thai) coworker who's a whiz at the phones shows up by my side and is like, "Done," and she tells the customer that she changed his order, and he goes back to his table.

. . .

Besides my standard spiel where I tell customers who try to retroactively change orders that it can interrupt the kitchen and cause mistakes in their orders and those of others, I also now make sure to tell them that we have multiple languages spoken in the kitchen, and it can be very difficult to go back and find out where the food is in the cooking process and change what's needed to be changed if it can even be changed, and to communicate that information verbally rather than in writing, instead it's much much better to have everything correct in writing on the initial ticket, and so mistakes happen and we will do our best, but please try to have the entire order information correct when the order is given at the table in the future, please.