Vegetarian!!! Why?
Actually most curry sauces lend themselves to vegetarian dishes quite well, only one i can think of that doesnt is the tomato based sauce used in Rogan josh which pretty much only works with mutton/lamb.
This is a basic "covers anything" curry sauce that i sometimes make as the ingredients are all things i have in the cupboard or fridge all the time.
Dry fry in a large pan; 1 teaspoon of fenugreek seeds, 1 teaspoon of cumin seeds and 1 teaspoon of coriander seeds, when they have browned pour them into a pestle and mortar and grind to a powder.
Take the ground spices and blend them with 2 chopped cloves of garlic, 2 chopped fresh green chillies, a piece of ginger about 1" square chopped and a handfull of fresh torn curry leaves (if you cant get curry leaves then just leave them out, it wont effect the flavour that much).
Heat 2-3 tablespoons of ghee or clarified butter in a wok or large pan (or if youre really flash a khari) and add a tablespoon of mustard seeds, as soon as they start to pop add the blended spice mixture and stir fry for one minute.
Add 2 large chopped onions and a teaspoon of Tumeric to the pan and continue frying until the onions are soft and golden, then add your choice of vegetables (pretty much anything can work but classics are cauliflower, lentils, potatoes and spinach) and stir fry for another 4-5 minutes.
Stir in a tin of chopped tomatoes, 10floz of water and a 14floz can of coconut milk and bring the sauce up to simmering point, keep stirring so it doesnt stick. Let the sauce simmer until all the vegetables are cooked to the texture you like them and then remove from the heat.