Soufflé is a typically vegetarian dish. Not particularly simple, but very delicious. I made a celeriac soufflé the other day that turned out a success:
Preheat oven to 200° C/ 400° F.
Peel and dice a celeriac bulb and cook in salted water until soft. Mash or purée.
Make a roux with a tablespoon of butter, a tablespoon of flour and enough milk to make it a sauce consistency.
Mix the mashed celeriac with the sauce, a few tablespoons of grated cheese, some tarragon or parsley, and two egg yokes. (Make sure the mixture is not too hot, or the yokes will curdle)
Beat egg whites to the soft peak stage (à la Delia Smith) and fold gently into the mixture.
Spoon into a buttered soufflé dish and bake for about 30 minutes until golden.
Serve with a crisp salad.