Toast chilies and onion in a dry cast iron pan over medium high heat for about 3-5 minutes. They will start to soften and release aroma. Careful not to burn - they will taste bitter if burned.
Remove chilies and onion to a blender. Add achiote powder, cinnamon powder, garlic, agave nectar and warm chicken broth. Blend until very smooth.
Heat lard in the cast iron pan over medium high heat. Pour in Red Chile Sauce and simmer for about 5 minutes. Remove from heat and cool completely.
Coat halibut fillet in about 4 tbsp. Red Chile Sauce. Grill over charcoal, skin side down, for about 8 minutes or until fish turns opaque in the middle and starts to flake when you push on it with a fork. While you are grilling halibut, add the corn to the grill and rotate as each side gets a little charred.
Cut the grilled corn off the cob and toss with cilantro and fresh squeezed lime. Serve over grilled halibut.