Tempura is a popular Japanese food in the States and as well-known as sushi. It is not too difficult to make.
You can use whatever your favorites fish and vegie for tempura. Here are some of my suggestions.
Shrimp, squid, scallop, any white meat fish, eggplant, sweet pepper, pumpkin, sweet potato, oyster mushroom, carrot, or even avocado will make nice tempura.
If you want pumpkin, I think Kabocha squash is the best for Tempura. Scoop out all the inside of it.
Also, I think regular American sweet potato is a little watery for Tempura. Purple skinned Asian sweet potato is preferred. You can find it in an Asian/ Chinese/Korean glossary store but if you live in Astoria NY, a Trade Fair supermarket near 30th Ave. station carries it.
The key to make lightly crisp tempura is how not to develop gluten in batter. Gluten, the protein found in flour is necessary composite when you make bread dough and noodle, but it is a nuisance to the delicate fries unless you want heavy, chewy tempra. So keep the batter cold with ice and do not mix much. Adding a spoon of baking powder and using beer partially instead of water also help not to activate gluten.
How to Prepare
Slice sweet potato and pumpkins, and microwave them for a few minutes.
Do you know Kakiage?
Kakiage is a variation of Tempura, use 3 or more different ingredients usually sliced or cut into thin strips or chopped roughly. Probably you do not find Kakiage in a menu of upscale restaurant, but very popular at a casual restaurant and at home.
How to cook
First, pour generous amount of frying oil in a large pan and heat.
In a medium sized bowl, pour a cup of cold water (or you can use cold beer partially) and add a couple of cubes of ice and an egg. Mix lightly and add flour into it. You can add a spoon of baking powder here as well.
It is fine if the powder is not completely mixed with water.
Check the temperature of oil now. Drop a tiny amount of batter into oil. When it sinks and soon float up, it is the best timing to start frying. If it does not sink, the oil is too hot. If it sinks and does not float up within a few second, you need to heat a few more minutes.
Do not touch it until the batter gets solid.
To make Kakiage, pour some batter into a bowl of sliced vegie-shrimp, and sprinkle a spoon of flour into it. Mix gently.
Using fingers, pinch a small amount (about 1-2 spoonful, maybe) of Kakiage mixture, and gently put it into oil.
When it is fried, place it onto a paper-lined tray.
I like to mix a cup of Iriko soup stock, 3 tbs of sake, 2 tbs of soy sauce, 1 ts of salt and 1-2 tbs of sugar to make Tempura dipping sauce.
Tempura is great to eat with rice, noodle or even just with beer. Enjoy at your own home.
I have the recipe in Japanese, too.