Prefer tea dust over crumbled tea leaves at home

I cannot find a tea that matches your description, because the combination of Japanese style flavor and color and whole, small leaves is conflicting. I'm trying to find more information about Nepalese and Bhutanese green teas, but unfortunately they're not as well known or documented.

Perhaps we can work together to coax your memory and pin it down more?

I have four immediate questions to help pin it down more:

• Was the brewed tea yellowish at all, or a true green shade (less common)? I'm assuming you meant a true green when you said "green" but it isn't terribly specific.
• Were there any sweetness to the tea?
• What was the "nice aftertaste" you describe like?
• Can you think of any other flavor or smell descriptions that apply?

Here's what I get from your description: The use of whole leaves, not fragments and not pearls, rule out several categories of green tea, and is probably the most useful information. It is also unusual for Japan, which tends to fragment the leaves and roll them into little spikes called sencha rolls. Many Japanese teas include parts of the tea plant other than just the leaves (buds, twigs, etc).

The lack of a yellow tinge to the brewed tea suggests a Japanese, rather than Chinese, style green tea. This is the result of cooking the leaves in processing using steam (Japan), rather than a hot pan (China), the latter of which produces "aroma molecules characteristic of roasted foods (pyrazines, pyrroles) and a yellow-green infusion" (On Food and Cooking, pg 437). If there were grassier notes, that would further suggest a Japanese tea. Ceylon green teas are kin to assam tea, and tend to be darker in color, so that's right out.

The energetic effect and bitterness suggest a higher caffeine and phenolic compound level than normal for a green tea, and rule out something like Dragonwell which is naturally quite sweet. Which is a shame, because Dragonwell is phenomenal, and varieties can have the color and leave shape you describe.

EDIT: Try sencha!

Based on your description, I think it's the best way to go forward, followed by kabusecha. "Grassy" is a descriptor usually attached to the Japanese way of preparing green teas. I always think of it as the flavor of sencha, although it applies to other Japanese green teas. I think your best bet would be ignoring the problem of leaf rolling (there may be some tea manufacturer with an eccentric way of handling it) and trying a variety of top-quality senchas to see if you can find one with a similar flavor. The best ones will be made from very young, small leaves and buds.

There are couple of factors at work when re-steeping green tea: temperature, time, and the quality of the tea (the size & way it's been processed). Green tea is supposed to be brewed with water that's been brought to boil and allowed to cool to 167 - 176 degrees Fahrenheit (though many people simply heat the water to that point or what they eyeball as hot but not boiling). Green tea is typically steeped for 1 - 2 minutes. And green tea, especially loose leaf, but also with higher quality tea bags, has furled and sometimes rolled leaves. The lower temperature, the short steeping time, and the curled leaves mean that flavor is still left within the leaves even after multiple steepings. The leaves continue to expand and release in subsequent baths. I don't, unfortunately, know any of the exact science--what's being released when, etc.

However, a possible alternative to boiling & brewing individual teas when done or simply using more tea (the typical choice when brewing larger quantities), you can bring your water to temperature, steep, pour it into a preheated or heat retaining container, and repeat the cycle until you've brewed your multiple cups in one go. As far as I know the tea leaves don't need to 'rest' in between brewings.

The reason green tea can be re-steeped is also the reason most black teas can't. Black tea is subject to boiling water for a longer period of time (typically Western use is 3 - 5 minutes; some cultures favor an even longer steep for the deeply bitter tannins). The hotter and longer steep pulls more flavor out of the leaves faster. Some black teas, especially high quality whole-leaf, can be re-steeped, however. Most bagged black teas--and a lot of loose leaf--can't.

The heat & steep time is dictated by the processing of the tea once it's picked. Green tea has minimal processing--pluck, wilt, shape & dry. Black tea is allowed complete oxidation (called fermentation). Fermentation breaks down chlorophyll, releases tannins, and forms many of the taste & aroma compounds that typify black tea. Oolongs and other varieties are subjected to varying degrees of fermentation. The size & shaping of the tea leaf--allowed to remain whole, broken, rolled, or (for most bagged tea) cut into fannings and dust, also affects how tea should be initially steeped and whether it can be re-steeped. Highly rolled oolongs, for example, often hold up to more steepings than green tea and are even said to taste best only on the 3rd or further steeping.