Combine all ingredients except roast in a mini chopper and chop to a fine paste. Add olive oil to get proper consistency.
Cut a deep pocket in roast but do not cut through. Spread paste liberally in pocket and coat all outside surfaces. Wrap roast in 2 layers of heavy-duty aluminum foil and seal edges well.
Place 12 to 13 charcoal briquettes in bottom of vented metal coffee can. Start charcoal and allow to heat until all surfaces are glowing. Place foil wrapped roast in can seam side up and cook for 45 minutes.