Preheat broiler to high. Peel the papery outer skin off your tomatillos and wash them well, as well as the tomatoes and jalapenos.
Cut all of the vegetables in half and remove any stems. Seed the jalapenos, leaving the seeds in only one half of one of the peppers. This will make for a salsa with a moderate amount of spicy kick. If you prefer your salsa mild, use only one jalapeno and seed and stem the pepper entirely.
Place cut veggies on a baking sheet lined with aluminum foil and broil, until charred in spots, about 4-5 minutes per side depending on the heat of your broiler. Remove veggies and let cool completely.
In the bowl of a food processor or blender combine the roasted vegetables, minced onion, garlic, cilantro (if using), water, olive oil and lime juice. Season with two big pinches of sea salt and pulse to combine until the salsa reaches your desired consistency.
If you prefer a chunky salsa, keep the amount of pulses to a minimum, for a more sauce-like consistency, pulse for a bit longer.
Taste and adjust seasonings if necessary. This fresh salsa is ready to eat immediately, but tastes even better after a few hours in the fridge to let the flavors meld together; so if you can, wait a bit before serving.