Combine garlic, first listed green onion, thyme, peppers, vinegar, water, brown sugar, allspice, nutmeg, and first listed salt in a food processor and blend on a high speed until smooth. Transfer to an airtight container and store in the refrigerator until ready to use.
Cut flesh of mango around pit into large pieces. Grill mango pieces until they are charred on all sides. Allow to cool before dicing into 1/4" pieces.
Remove skin and pit from avocado and in a medium bowl mash avocado and fold together with diced grilled mango, jerk paste, lime juice, and kosher salt until evenly combined.Top jerk guacamole topped with second listed scallions and serve with sides of choice.