When I was working on the keerai (spinach) pittu recipe last week, I needed a curry to go with it. Jed was still visiting then, so I went for something vegetarian — I was also trying to use up various tired veggies in the fridge. This is a really basic approach to a default Sri Lankan vegetable curry. (It’s usually referred to as a ‘white’ curry there, because it doesn’t contain red chili or turmeric, though it’s actually more of a light tan.)
Step 1 — Chop onions (always step 1 for curries). If you’re feeling energetic, add in some chopped ginger and garlic. Heat oil and sauté with mustard seed, cumin seed, and salt until onions are golden-translucent. Add pepper if you want; if you like fenugreek or fennel seed, feel free to stir some of those in too. (If you put in lots of fenugreek, which is a galactagogue, white curries are traditional preparations for nursing mothers.)
Step 2 — Sauté. Add in whatever veggies you like, based on cooking time — root vegetables cut small and added at least 10 minutes before softer veggies like bell peppers or eggplant. I had some green chilies, tired shredded carrots, chopped sugar snap pea pods, curry leaves, and I’m not sure what else got tossed in. 
Step 3 — Add some water and simmer a bit ’til veggies are cooked through. Taste and see if you’d like a little lime juice for balance — I usually do. You could stop and eat it at this point.
Step 4 — If you’d like it a little more rich (recommended), add in a can of coconut milk (or cow / goat / etc. milk is fine too) and simmer, stirring, until well blended. Taste and adjust seasonings.
Step 4 — For added heft, boil some eggs, slice in half, and slip those in too. Yum.
