Possibly because it's typically used to make a beverage, but most people forget that, by any definition, tea is an herb. It's the young growing tips of the tea tree, Camellia sinensis that can be used fresh, or dried, or processed in many ways.
Where the different kinds of teas are processed as follows:
White tea: Wilted and unoxidized
Yellow tea: Unwilted and unoxidized, but allowed to yellow
Green tea: Unwilted and unoxidized
Oolong: Wilted, bruised, and partially oxidized
Black tea: Wilted, sometimes crushed, and fully oxidized
In Japan, green tea is finely milled to make matcha, green tea powder, which is not only the tea used in the Japanese tea ceremony, but is also used as an herb to flavour other dishes. In Britain, black tea is often used to flavour and moisten cakes. People forget that tee is often used to cook with.
Indeed, a little tea added to a smoker greatly enhances the flavour of the meat or fish being smoked. It's even very easy to make an indoor smoker for fish or meat strips at home with a wok. Mix sugar and tea leaves together (add hickory or applewood shavings if you like). Line the base of a wok with kitchen foil and sit the smoking mix in a foil cake liner. Sit this in the base of the wok and place a trivet on top. Place over high heat and heat until the smoke appears. Add your meat or fish on the trivet, close with a lid an seal with foil. Smoke for about 20 minutes, or until the meat is cooked.
Below is a classic Japanese recipe for a green tea flavoured cake:
Green Tea Kasutera
2 tbsp warm milk
1 tbsp matcha (green tea powder)
5 large eggs
150g icing sugar
3/4 tsp baking powder
105g plain flour
icing sugar, for dusting
Crack the eggs into a bowl and beat until frothy. Gradually work in the icing sugar with a whisk then continue beating until the mixture drops as ribbons from the whisk (about 15 minutes). Mix together the milk and honey (the warm milk will make the honey more liquid) then work this into the egg and sugar blend.
Sift together the flour, baking powder and green tea powder into a bowl. Gently fold this mixture into the egg mix until just combined. Carefully pour the batter into a greased and lined springform cake tin. Transfer to an oven pre-heated to 180°C and bake for about 35 minutes, or until the cake has risen, the top is golden brown and a skewer inserted into the centre of the cake emerges cleanly.
Remove from the oven, and allow to cool in the tin for 10 minutes. Turn out of the tin and place on a wire rack to col completely. Store in an air-tight tin and serve the following day (the cake will mature over night if stored).
Originally the cake would have been steamed rather than being baked and, indeed, steaming does give a cake that is wonderfully springy and light.