This next photo is NOT how you should use your zester:
Zester on bottom, lime on top is a big fat NO.
Okay, this isn't the best photo but I think you'll get the point. There are different types of zesters but most have these curved sides:
Those curved sides are there for a reason. Yes, it's true!
You want those little curved sides to face up with item to-be-zested underneath:
Making sense, right?
When your zested item is on the top of the zester (see photo 1) you cannot see how much zest you are actually taking off:
Anything below that first, thin layer is bitter. So basically, the center part (where it is white) is bitter and you don't want to zest that deep. Again, with the lime on top of the zester, you can't tell when you hit that white part. AND you can't evenly zest what you are zesting.
Wow, this post is so zesty.
Look, when you can properly see what you are zesting, you can evenly zest!
So even and not too deep. Let's celebrate.
How glorious. Look, all that yummy zest is contained within the curves of the zester. You can easily scoop it out and measure for baking and cooking.