The prik yuet is a mild sweet chili often called the Thai bell pepper, and if it isn't available then bell peppers may be substituted.

The thickening agent used is arrowroot, but you could easily use cornstarch or rice starch instead.

The Msg is of course optional.

Maggi Seasoning is a dark (almost black) sauce derived from soy sauce, and widely used as a seasoning in the orient. It is freely available in specialty and oriental groceries in the West (not surprising as Maggi, part of the Nestle group is a Swiss company).

Finally let me say that kuaitiao dishes are common 'hawker' food in Thailand and are usually prepared fairly blandly. The bowl of noodles is then seasoned to taste from the seasonings on the table. As a rough guide I include my wife's final preparation at the end of the method.