Add some olive oil to a cast iron over medium to medium-high heat. Cook the peppers for about 5 to 10 minutes, until they are starting to blister.
Add the onions and garlic cloves to the pan and cook until they start to soften, about another 5 minutes.
Remove the peppers, onions, and garlic from the pan. When the garlic has cooled enough to handle, remove the skin.
Place the peppers, onion, garlic, cilantro, lime juice, water, cumin, and salt to the base of a mini food processor or blender.
Blend until well combined. You want a salsa that is thoroughly blended while maintaining a bit of its texture. Add a bit more water if it is too chunky.
Taste for seasoning and serve.