Preheat your oven to 400 degrees. Place your tomatoes, onion, and jalapeno on a large baking sheet. Drizzle with enough oil to lightly coat the vegetables. Bake for 40-45 minutes, or until a nice char is on your vegetables.
Once the vegetables have cooled for about 5-10 minutes, put the vegetables, garlic, and cilantro (in batches, if needed) in a food processor or blender, and pulse to your desired consistency. Place the mixture in a large dutch oven, and put on medium-high heat on your cooktop.
Add the lime juice, cumin, and sea salt to the mixture in the dutch oven. Cook down to reduce the liquid for about 20 minutes. Let cool, and serve with chips of your choice.