My limeade is often a mix of lemons and limes. Not by design. Just that I tend to have both on hand so I use them both. Limes tend to yield about 1/8 cup of juice, and I would say lemons are similar. That said, if your lemons are bigger than your limes, well... you do the math. FACT: I tend to prefer limes over lemons, but lemons can do some cool stuff. Everything from cure acne to dandruff, according to the Huffington Post. You can see all of the weird things lemons can do here.
So juice the lemons and limes so you have 3/4 cup of juice (1/2 lime and 1/4 lemon). You can of course adjust this anyway you see fit.
Now we are gonna make our cilantro simple syrup. We need 1 cup of syrup which is why you use 3/4 cup sugar and 3/4 cup water. The basic recipe is this for simple syrup: for the desired amount, you use 3/4 both sugar and water.
Add the sugar and water to a small sauce pan and warm it over a medium-low heat. You just want to heat it enough to combine. Don't boil it.
Add in the 2 cups of chopped cilantro. Honestly, you don't have to measure it out. That should be about one bunch, the size you get in the grocery store.
Make sure the cilantro is mixed into the syrup and let it steep for about five minutes. Then strain it out. Seriously... do not leave it in. It will wilt, turn brown, get gross, and you will blame me... even though it is your fault for not following directions. FACT: Some people love cilantro and others hate hate hate it. Why? Cuz they are broken. No really, it's like science and stuff. People who hate cilantro are genetically different, like mutants.
Combine the citrus juice, simple syrup, and two cups of water in a pitcher. Mix well and place in the fridge to chill.
Serve over ice with slices of limes and fresh cilantro sprigs.