The first time I ever encountered the term ‘mixed’ in the name of a dish, I was in England already. When I browsed through the menu in a Chinese restaurant and saw dishes like ‘mixed vegetables’ or ‘mixed meat’, I was quite surprised. Such dishes do not exist in traditional Northeastern Chinese cuisine.
I think I do like the idea of ‘mixed’ though, just imagine how many different nutrients you can take in one dish. :)) However, in Northern Chinese cuisine, you will rarely find this kind of combinations in a single dish. What is much more common is to have one or two “main ingredients” in each dish, possibly accompanied with some other ‘supporting’ ingredients (especially when the main ingredient is meat, or seafood).
For example, a lamb dish will not contain other types of meat as main ingredient. The taste of the dish will focus on the lamb, which can be cooked with an adaptable method( for example ‘Chinese lamb pieces on toothpicks (Ya qian rou)’). Same with other types of meat or seafood (for example, ‘homemade stir fried squid’ ). In contrast, the taste of “mixed meat” dishes is generally more focused on the sauce, and the mixed meat is only lightly boiled.
Sometimes the main ingredient is accompanied by one or two types of vegetables, which we normally call ‘supporting ingredients’, as they usually come in small proportions. Their main purpose is to ‘help enhancing’ the taste of the main ingredient (meat, fish/seafood). For example, in stir fried (big) spring onion or leeks with lamb slice, the spring onion can help get rid of the ‘lamb…ish’ smell, and give it a fresh taste; or for getting the taste from the meat (or fish /seafood), so the vegetables themselves become tasty, for example, potato in‘Hong Shao Rou’ / ‘braised/stewed/red-cooked’ beef. However, again, it is rare to find more than… say three different types vegetables accompanying meat (or fish or seafood) in a single dish.
As for vegetable dishes, combinations are a bit more flexible. We can have just one main vegetable with a couple of ‘supporting’ ingredients, but one can also find combinations of different types of vegetables with equal proportion. From the recipes I have posted, probably you have already noticed that there is no more than three different types of vegetables in one dish, for example,‘Di San Xian’ / stir fry aubergine, potato and green pepper.
If you read Northern Chinese recipes, you might have noticed that the ingredients section of the recipe is usually split in two parts: the first part is called ‘main ingredient’, and the second part is called… something like ‘accompanying/supporting ingredients’ and then you will find the necessary seasonings. And the name of the dish then is made up using the main ingredient only.