Apply lemon juice to all sides of tri tip... use plenty. Sprinkle garlic salt, season salt, garlic powder, and "Tones Cajun Seasoning". You can also add "Rudy's Rub" for a little more spice. Marinate over night. Cook it on a grill approximately 45 min. to an hour. We take it off the grill at 135 deg. Fahrenheit (54 deg. Celsius) because we like it rare. We have grilled 24 of these tri-tips and fed approximately 200 people for a church function.
Can also smoke it in a water pan smoker and use a mopping sauce. Enjoy!