This is hands-down my favorite noodle dish to eat and cook. It comes from my mom's home region of northern Thailand. This dish is very reminiscent of the popular Japanese tonkotsu ramen. The coconut curry is fortified with a very rich broth. "Khao" is the Thai word for rice—in this case rice noodles—and soi means "to cut." So this dish was originally made with hand-sliced rice noodle sheets, but the modern version is adapted for thin wheat noodles.