I am looking for an alternative to a procedure that my wife uses. She has been doing this for a very long time, and is very resistant to change. She takes a metal ladle, puts about 1 oz of vegetable oil in it, then holds it on the electric stove burner until the oil bubbles. Then she adds Geera (Cumin) to the oil. This is then added to the stew pot. One possibility is a very small metal pot, but I haven't found anything suitable. Maybe there is name for something like this that would help me find it. 
Ajitsuke tamago are likely a culinary descendant of lu dan, Chinese soy sauce marinated eggs. Lu dan are also frequently added to soups, and can be hard or medium boiled. As a very old Asian food, they exist in other Asian cuisines as well, including Korean and Filipino. What's interesting is the lack of marinated, but not pickled, egg recipes from non-Asian cultures.  Every country in Europe has some form of pickled eggs, but savory marinated eggs doesn't seem to be something that Europeans discovered before trade with China. 