Place lemongrass, apple cider vinegar, lemon juice and extra virgin olive oil in a blender or food processor. Pulse for a 5 seconds to chop up the lemongrass.
Transfer the mixture into a bowl and add Worcestershire sauce, ginger, garlic, red onion, sea salt and black pepper. Mix well.
Score the chicken leg quarters about 2-3 inches long and 1/4-1/2 an inch deep 3 times on both sides to allow the marinade to infuse the chicken.
Place chicken in a gallon sized zip top bag and pour the marinade on top. Remove the excess air in the bag and seal it well. Roll the bag on the countertop to allow the marinade to distribute evenly around the chicken.
Marinate the chicken for at least 4 hours or overnight in the fridge.
Prepare the Annatto Seed Oil by heating the avocado oil in a small saucepan over medium-low heat.
Add the annatto seeds and stir it for 3 - 5 minutes until the oil turns into a bright yellow-orange hue.
Remove from heat and transfer to a bowl to cool.
To cook the chicken, preheat the grill over medium heat.
Remove the chicken from the bag and drain off excess marinade.
Place the chicken on the grill and cook for 10-12 minutes on each side, flipping every couple of minutes and basting with the annatto seed oil so it cooks evenly and one side doesn't get burnt.