Heat a grill on medium-high heat. Smear 1 teaspoon of the olive oil over the bottom of a shallow aluminium pan. (Alternatively, you may form a tray out of a double layer of heavy foil. Be sure to place it on a cookie sheet for stability.)
Mix sugar, dry mustard, cinnamon, paprika, cocoa powder, chili powder, cumin, pepper, and salt.
Coat both sides of the salmon filet with remaining olive oil. Place in grill pan. Sprinkle generously with the cocoa spice mixture and pat down. (You may have some spice mix left over. Store in a glass jar in a cool, dark place up to 6 months.)
Grill salmon about 10 minutes per inch of thickness, until salmon flakes easily with a fork. Do not overcook or it will become dry.