It is very easy to convert traditional meat recipes into vegetarian just be swapping a few of the ingredients. Below I list some meals that you might want to cook when you have a vegetarian guest for a meal, and how simple it is to make them a tasty meal without the meat.
In this recipe you will need to swap the mince that is traditionallly used in the spaghetti sauce with a vegetarian equivalent. You can get textured vegetable protein (tvp) which is a mince made just from vegetarian ingredients. This can come frozen or dried. If you use the dried version you will need to add extra liquid to your sauce to make sure that it doesn't dry up too much. You will also need to taste it to make sure it is salty enough as different brands add different amounts of slat.
If you are cooking roast potatoes you will need to make sure that you don't use animal fat to cook them. Vegetable oil will make them lovely and crispy and if you add some garlic and rosemary they will have a lovely flavour. To replace the meat in the roast you can use a nut roast or a vegetable bake. These come in packet mixes or frozen but if you want to make your own it is very simple. I mix breadcrumbs, crushed nuts and garlic with mixed herbs and salt. Mix it all together. Then I bind with a mixture of water and vegetable oil or you could use an egg instead. I put it in the microwave for 5 minutes then crisp up in the oven for 20 minutes then slice before serving. It is very easy to buy vegetarian gravy but I usually make my own. I put thinly sliced onion and mushroom in a saucepan and cook for a few minutes with a tiny bit of water. Then I add tomato paste, mixed herbs and marmite. Then I add boiling water and thicken with cornflour.
If you are making a chicken stir fry and putting it is wraps you could replace the chicken with chicken style strips which can be bought frozen or refrigerated. However, if you can't get hold of these you can always use tofu. If you deep fry this first it will work better when you come to mix it with the vegetables. Neither of these have much flavour so you will need to add a spicy sauce or alternatively you could marinate the tofu first. You would do this by either just using soya sauce, or using tomato paste with some chilli powder if you want it to be spicy.
Curries are very easy to make vegetarian. Usually if you just leave out the meat the meal is still as delicious. However, it will lack in protein. You can easily make up for this by making a dahl from onion and lentils and curry spices. This is quick and easy as you just put the ingredients in a saucepan and add boiling water and wait for it too cook!