How do you express a citrus peel?
Use a vegetable peeler to remove a 2 to 3 inch strip of lime peel. Hold it between your thumbs and forefingers with the colored zest side facing down over the drink. Squeeze the edges of the peel together and twist. A fine spray of citrus oil will land on the surface, and you'll smell it before you see it. Rub the peel around the rim of the glass and drop it in for color.

Why is this drink built differently from a normal iced latte?
Carbonated drinks are the exception to the usual iced-drink rules. Pour the ginger beer directly over the ice first, then layer the chai and lime in slowly. Stir gently. Building the drink in a separate pitcher or shaking it with the ginger beer kills the fizz, and the fizz is half the point.

Can I make this a dirty chai limeade?
Yes, and you should at least once. Pull a single or double shot of Frothy Monkey Howler Espresso and add it after the lime juice. Stir gently because of the carbonation. The espresso adds enough caffeine to push the drink from afternoon refresher into morning fuel without bullying the chai spice.