If I make an example for this expression, it could be:
점심에 뭘 먹을까? 국수로 하지. = Any idea what to have for lunch? Let's have noodles.
Here, -로 is used to describe a result, selection, or conclusion.
In 연필로 쓰다, -로 is used to describe a method, tool, or material used to do something.

XKL, 고마워요.
아까 제 점심에 ayam panggang nasi로 핬어요

If I remember correctly, nasi means noodle and mi means rice. Right?

XKL, you switched them around. Nasi = rice; e.g. nasi campur (mixed rice), nasi padang, nasi goreng (fried rice), nasi puteh (white rice), nasi bryani.

OK. 謝謝.
I like southeast asian food. But, there is only one southeast asian restaurant in my city. So I just have to take whatever they have. It is a Vietnamese restaurant, so rice noodles are the main items. They also have Thai style tomyamkung.

Aren't you in Seoul ? There is Thai and Vietnamese food in Seoul and Singapore seafood too.

[귓속말 입니다.]

Ummm... Telling directions can be confusing. I will send you an email.