Grind cinnamon, cloves, peppercorns, red chillies, 4 cloves of garlic and one inch ginger with about 1/2 cup palm vinegar or red wine vinegar. Adjust the amount of vinegar as required to grind a smooth taste. Slice the remaining 4 garlic cloves, cut the remaining 1-inch ginger into julienne's and set aside.
Heat 2 tablespoons oil in a skillet, fry mussels on medium heat for about 5-6 minutes, until the moisture reduces. Remove to a plate and set aside.
In the same skillet, heat remaining oil, add garlic, saute few seconds, then add ginger and saute until ginger and garlic are fragrant.
Add the ground masala paste, saute on medium heat, until the masala leaves oil.
Rinse the blender jar with about 1/2 cup of red wine vinegar, add it to the pan along with coconut feni* sugar and salt to taste. Mix everything well, check for seasoning and adjust accordingly. Add more vinegar or sugar to balance the tang and spice. Cook on medium heat until the mixture begins bubbling, about 2 minutes.
Add the fried mussels, simmer another minute. Switch off the heat, let the pickle cool. Store in sterilized container. Let it mature for 1 -2 weeks at room temperature. Once you open the bottle, you may store it at room temperature or in the refrigerator. Remember to use a clean, dry spoon each time.