Add tomatoes, jalapeño and onion to a medium sauce pan and cover with water.
Place on medium heat and bring to a boil.
Turn off heat and let “steep” for 10 minutes (tomato skin should be split and jalapeños should have changed color a bit.)
Strain the tomato, jalapeño and onion into a blender base with a splash of the cooking liquid.
Add lime juice, cilantro and salt.
Blend until desired consistency. (Pulse for chunky and Blend for smoother.)