Position oven rack in top ⅓ of the oven. Preheat broiler. Place onion wedges, garlic cloves (with skins on), lime and jalapeno on a baking tray. Broil for 7 minutes, turning onions and jalapeno halfway through.
Allow the aromatics to cool for 15 minutes. Remove garlic cloves from skin and juice the lime.
Place onion, peeled garlic cloves, lime juice, jalapeno, salt, and cumin to a food processor. Pulse for 10-15 seconds.
Add the tomatoes and ¼ cup of the mint, pulse for 30-45 seconds to combine. Taste for flavor, add additional salt or mint if needed.
Mint flavors can vary greatly from plant to plant.
The mint flavor will become more pronounced as the salsa sits. If making for same-day use add mint to taste- usually a ⅓ cup total. For advanced preparation we recommend starting with a ¼ cup of mint and testing for flavor right before serving, add more mint if needed.
To reduce heat use only half the jalapeno or remove seeds and veins.