Our youngest daughter became a vegetarian when she was a teenager some six years ago and that led us as a family to explore the delights of vegetarian food on a regular basis.
Most of our recipe ideas are from books or websites rather than original (and Sarah has taken most of them with her). But here are a few ideas which you can track down through your own research.
Soups: ideal for weekend lunches and especially at this time of year. The family favourites are butternut squash or parsnip and apple or leek and potato.
Roast vegetable stews. These are my favourite vegetarian meals. Basically, you roast a big tray of interesting root vegetables in the oven for about 20 mins and then stew then gently in a casserole dish and add some beans or pearl barley or perhaps a cheese topping. I tend to cook very big batches and freeze smaller portions. We normally serve them with a baked potato.
Lasagne: there are excellent vegetarian recipes for a bolognese type sauce with red lentils which forms an excellent filling for a vegetarian lasagne: just as tasty as the meat versions.
Special occasions. We faced the problem some years ago of what to cook the vegetarian in the family for Christmas dinner. Thankfully Delia Smith has come to the rescue. Her Parsnip Roulade recipe is absolutely superb but is I think the most demanding thing I cook all year. There are about five different stages but it always turns out really well.
(If you want to cook the Parsnip Roulade you can find the recipe here