Preheat the oven to 450ºF and line a baking sheet with foil. Cut the stems off the tomatoes and cut them in half. Peel the garlic and chop the onion into large chunks. Place the tomatoes, onion, garlic, poblano, and jalapeño on the baking sheet and drizzle with olive oil. Toss the vegetables in the oil until coated.

Roast the vegetables in the oven for 30 minutes, stirring halfway through, until shriveled, blistered, and slightly brown. Remove from the oven and allow to cool.

On a cutting board, remove the skin from the poblano and slice off the stems. Slice the peppers open lengthwise and scrape out the seeds.

Transfer the peppers and all remaining vegetables (with juices) to a blender or food processor. If still warm, place the blender in the refrigerator until cooled.

Add fresh cilantro leaves, lime juice, salt, sugar, and cumin to the blender with the roasted vegetables. Pulse until well mixed but still slightly chunky. Adjust seasonings if needed.

Serve immediately or refrigerate overnight for a more mellow flavor.