Place the oven rack 3 inches from the top of the oven. Turn the oven to broil. Cover a baking sheet with tin foil then coat it with cooking spray.
Place the washed tomatillos and Hatch chiles on the baking sheet. Place into the oven under broil for 4-5 minutes, or until blackened.
Flip the tomatillos and chiles over and place back under the broiler for 2-3 minutes, or until blackened.
Remove from the oven and place the tomatillos and chiles in a large zip lock bag. Seal and set aside for 5 minutes.
Remove the blackened skin and place the tomatillos into a bowl. Remove the blackened skin, stem, and seeds from the chiles. Set aside to cool to room temperature.
Place onion, garlic, cilantro, and lime juice in the bowl with the roasted tomatillos and chiles. Season with a dash of cumin and oregano, and sea salt and pepper, to taste.
Blend the salsa with an immersion blender until smooth. Taste and re-season with lime juice or salt, if needed.
Set aside to allow flavors to mingle. Serve with tacos, chips, burritos, eggs, enchiladas, etc.