Place the tomatillos, garlic cloves, and jalapeno chiles on a lined baking tray (you can use a silpat or foil to line the tray). Try to tuck the garlic under the tomatoes to keep it from burning.
Broil for about 15 minutes, turning frequently, until evenly roasted and charred. Remove from the oven, and set aside to cool completely.
Add the roasted tomatoes, garlic cloves, and jalapenos to a blender or food processor. Add the cilantro and water and puree until completely smooth. Start off with 1/2 cup water and increase up to a total of 3/4 cup water as needed depending on desired consistency.
Season with salt and pepper. I prefer to chill the salsa in the fridge before serving, but it can also be served immediately.
Notes
You can easily make this salsa ahead of time and store it in the fridge for a few days, or freeze for a few weeks!