You can't get started directly at first. First, you should do odd jobs, kill fish and chickens, clean the kitchen and so on. It will take a long time, slowly give you a chopping block, let you cut vegetables, then give you a chance to side dishes and finally give you a chance to get started.
You worked for a month and paid you full salary, and then you paid 600 yuan. I think this boss has done a very kind job. Don't think he is shameless. If you change your boss, you may not be as good as him.
I used to be a catering minister in a star-rated hotel, so I know some rules about the kitchen. Like an independent kingdom. It is common for a master to take an apprentice. Apprentices often don't get the full salary after getting the normal salary, even if they are good at technology, so they take out some.