「cost」と「cheap」の使い方

This is what I've really got to learn to cook. It's vegetarian char siu, which is Cantonese-style BBQ pork. This is a vegetarian one, so it's made with gluten and spices. The black parts, rather than being burnt meat, are a kind of fermented black bean sauce. I ate this in Hong Kong. It was so delicious, and I keep thinking about it and how to make it.

• fermented【形】発酵した (definition from Eijiro on the Web)

There are vegetarian restaurants in Tokyo, but...

× the cost is cheaper in Hong Kong.
○ the [food is/restaurants are] cheaper in Hong Kong.
○ the cost is lower in Hong Kong.

The vegetarian food in Hong Kong is generally more delicious, too.

"Cheaper" means "lower in price". "Cost" is a synonym for "price". That means that the incorrect sentence above means:

• The price is lower in price in Hong Kong. ← strange!

"Cost" or "price" is a number, so you should use "lower" or "higher". Use "cheap" for products.

If you happen to know a good recipe or tips for cooking char sui at home, please let me know, especially if you know how to cook the vegetarian version. The cost of making it at home is certainly lower than flying to Hong Kong to eat it again. If you know a way to get cheaper tickets to Hong Kong, though, I'd like to hear that, too!