Hong Kong has several famous restaurants, and one of them is one of the cheapest (the cheapest?) Michelin Star restaurants in the world. 
Tim Ho Wan, The Dim Sum Specialists is famous for exquisitely formed dim sum cuisine still served in its traditional fast-paced service with the abrupt but efficient Chinese restaurant service style.
We arrived when it first opened, so we only had to wait about 30 minutes. Make sure you push your way through the crowd to the host stand and give the host your party number. He or she will hand you a little slip of paper with your queue number. Then hover around and listen as the numbers are called. 
The nice thing about the restaurant being famous is that guests from all around the world come to the restaurant, so the hosts and many of the staff can speak English and will provide an English menu. The menu is a fill-in card in which you mark how many of each dish you would like to eat. 
Four people can probably split 9 dishes and leave with no leftovers. If you plan to explore HK, it’s best not to lug leftovers around, and dim sum isn’t as good when it’s warmed up. 
Make sure you order the baked BBQ pork bun. Every dim sum restaurant I’ve been to has a BBQ pork bun, and a lot of the ones I’ve had are the white, puffy steamed buns served in a bamboo basket. Well, these pork buns were wrapped in a milk bread bun and topped with a crunchy “pineapple topping.” Incredible. Order one full plate for yourself. 

from the TimHoWan website
Tim Ho Wan – The Dim Sum Specialists
9 Fuk Wing St, Sham Shui Po, Hong Kong

Megan’s Kitchen hot pot restaurant is featured on Sassy Hong Kong for having unique, fusion broths and a wide selection of a la carte hot pot components. In addition to the usual bone broths, the menu also featured Tom Yum, oxtail stew, tomato soup, and even apple and corn soup.

My brother, Chris, and his girlfriend, Desiree, joined us for dinner, and good thing! There was so much food! We ordered lamb, beef, shrimp, black mushroom fungus, a mixed plate of mushrooms, noodles, cuttlefish balls, and greens.

Before the pot of boiling broth arrived, the server placed a big multi-bowled platter in front of us with condiments and dipping sauces that we could blend for our upcoming soup. The pot sat in the middle of the round table on top of an induction burner, which was inset in the table under a white (burned)  tablecloth.

When the broth arrived, scores of plates of meat, vegetables, and noodles came out, and the cooking began! The whole concept is to be given raw items that you can boil in the broth to your desired doneness. Be sure to cook the cuttlefish balls all the way through.

Periodically, the servers will come around with pitchers of broth and refill your hot pot, which loses as much broth in evaporation as it does to being absorbed by the noodles and other items.

When you arrive, make sure you order the Sugar Cane Juice. It’s meant to complement the heat of the soup and cool you down. It’s quite sweet, but probably has comparable sugar to a soda pop.

At your seat you’ll have two sets of chopsticks and a little wire skimming basket. The basket and the second pair of chopsticks are intended for you to select and cook your foods without touching them to your lips. The other pair is for eating. (It doesn’t matter which ones you choose, as long as you stay consistent throughout the meal)

Reservations – even on weeknights – are highly recommended. Dinner rush is actually later in the evening – think 8p – so if you’re game for eating earlier at 5 or 6, you’ll probably be able to get a table in the next day or two.

from the Megan’s Kitchen website
Also, plan on spending a good bit of money, so eat cheaply (or splurge!) the rest of the day. And go hungry. 

Megan’s Kitchen
5/F, Lucky Centre, 165-171 Wan Chai Road, Wan Chai, Hong Kong
2866 8305