In a large skillet or a wok, heat the oil over medium-high heat and add the mustard seeds. If your pan is hot enough the mustard seeds should start to pop in about a minute. If you have a splatter screen use it to keep the seeds from popping out of the pan. Otherwise, stand back.
Add the onion and turn down the heat if they are browning too quickly. Cook the onions until translucent, about 4 to 6 minutes. Add the curry leaves, green chilies, and asafetida (hing) if using, and saute for a minute or two.
Add the coconut and the green beans. If they are fresh, stir fry for 5 minutes stirring occasionally. If you are using frozen green beans, test at this point to see if they are tender enough to your taste.
Some people like a bit of crunch left in their beans. If you feel they need more cooking or you’ve used fresh beans, turn the heat to medium-low, add 2 tablespoons of water. Cover and cook the beans for 5 to 10 minutes until they are almost done to your taste. Add another tablespoon of water if they seem to be getting dry.
Uncover the pan, turn the heat up to medium, and cook for another 1 to 2 minutes until the water has evaporated, stirring occasionally. Add salt to taste.
SHORTCUT: Use frozen green beans either left whole or cut into bite-size pieces.
BESIDES GREENS BEANS: This recipe works well with cabbage, brussels sprouts, broccoli, cauliflower, or even leafy green beans. I like to add corn to the green beans in the summer for sweet pops texture and flavor.
CHILIES: As always, use as much or as little of the fresh chilies as you wish. If you want the flavor without too much heat, slit the chili down the middle starting just below the stem end, remove the seeds, and use the chili intact otherwise. You can always fish it out at the end of the cooking time.
COCONUT: I get my frozen coconut in an Indian grocery. You can also find frozen coconut in well-stock grocery stores, or use desiccated (dry) unsweetened coconut. If using this ingredient, to equal 1/4 cup fresh coconut, use 6 tablespoons dry or desiccated coconut. Pour warm to hot (but not boiling) water to cover and briefly rub the coconut with your fingers to speed up the water absorption. Allow to hydrate for 10 minutes or up to an hour. Drain well and use it as fresh coconut in this recipe.