As an alternative to the approach given here, you could thin the sauce with 2 cups of water or vegetable stock, and then simmer the vegetables in the sauce. To my palate however this seems to produce a bland result that is often reminiscent of the luncheons I used to detest at school.
I generally recommend that you purchase a good brand of Thai curry paste if you don't want to make it from scratch, generally recommending Mae Ploy brand. However *all* commercially available curry pastes (including those sold in Thailand from 'cottage industry' makers) contain shrimp paste and fish sauce. If you want a strictly vegetarian product you will have to make the paste from scratch. Though the recipe given here produces a thinner sauce, rather than a paste, it does allow the flavors to mature and infuse before use, which is the essential reason for doing this.
Maggi seasoning sauce (made by the Maggi division of Nestle) is a commonly used flavorant in oriental cooking. It is a soy derivative.
The serving as separate items is typical of modern Thai restaurant practice, but in the home the dish would normally be served as a "one dish" meal over the rice.
(nam prik kaeng khiaowan) Green curry paste: Combine to a fine sauce consistency in a food processor or liquidizer/blender, and store in a well stoppered container in a cool place for at least 3 days before use.
Next we must prepare the rice. For this recipe I suggest a brown rice, prepared as the aromatic rice, known as khao hom
khao hom (aromatic brown rice): If preparing the rice in an automatic rice cooker:
"winnow" the rice to blow away any dust, and check that there are no stones present. Place the rice in the cooking container of a 10 cup rice cooker (or larger).
In a wok, heat the oil, and then briefly saute the chili, onions and ginger until aromatic.
Stir the oil and aromatics into the rice, stirring vigorously so that all the rice is coated with the mixture. Add the stock and water, and cook to completion.
If preparing the rice on the stove top:
Winnow the rice and check for stones.
In a wok, saute the aromatics, then add the rice to the wok, remove it from the heat, stir until coated with oil, then add the stock and water, and return to the heat. Once it boils, lower the heat to a gentle simmer, cover and leave undisturbed for 20 minutes.
Whilst the rice is cooking we can prepare the curry:
First we convert the basic curry paste into a curry sauce...
nam jim kaeng khiaowan (green curry sauce): In a saucepan over medium heat combine the ingredients and simmer for 5 minutes, stirring occasionally. Taste for flavor balance and adjust as necessary. Transfer to a sauce boat or small bowl.
To complete the dish you need half a cup each of various vegetables to make a total of 3 cups. I suggest cauliflower (separate the florets, and slice the stalk thinly), asparagus, baby corn (cut lengthwise in half), bamboo shoots, Thai eggplants (or standard aubergine, cut into balls with a melon baller), and snow peas.
Place these in a bamboo steamer and steam until barely cooked (they should still be firm and snap when bent).
Place the vegetables in separate serving bowls. Each diner then helps themselves to rice, a selection of vegetables, and the curry sauce. For flavor contrast the vegetables can also be eaten with any of the standard Thai dipping sauces (adjusted if necessary to vegetarian/vegan requirements).