If you've a lot of sweet veg in there, particularly root veg, caraway seed is the boy (about 1/2 tsp/litre).
If you've got a lot of Mediterranean type, fruity veg in there (aubergine, courgette, tomato etc) i'd suggest a handful of fresh herbs, woody ones from the start or soft ones at the end.
Agree with @Brother Blades, you can't go wrong with cumin