Combine marinade ingredients in small bowl. Place beef Tri-Tip Roast and marinade in food-safe plastic bag; turn roast to coat. Close bag securely and marinate in refrigerator 15 minutes to 2 hours, turning occasionally.
Remove roast from marinade; discard marinade. Pat dry with paper towel. Prepare gas grill for indirect cooking by lighting two thirds to one half your grill, leaving remainder off. When grill is hot (10 to 15 minutes), place roast directly above flames. Cover and sear all sides of roast, approximately 8 minutes each. Move roast to unlit area on grid. Cover and cook 14 to 16 minutes until medium rare (135°F) to medium (150°F) doneness, turning occasionally. Place vegetables directly above flames. Cover and cook corn 15 to 20 minutes; asparagus 7 to 11 minutes and onions 11 to 15 minutes or until tender, turning occasionally. Remove roast. Let roast stand 5 to 10 minutes. (Temperature will continue to rise about 5°F to 10°F to reach 145°F for medium rare; 160°F for medium.
Carve roast against the grain into 1/4-inch slices; season with 1 teaspoon lemon pepper. Sprinkle remaining 1teaspoon lemon pepper over vegetables; toss gently. Season roast and vegetables with salt and pepper, as desired.
Nutrition information per serving: 245 Calories; 90 kcal Calories from fat; 10 g Total Fat; 2.8 g Saturated Fat; 0.2 g Trans Fat; 0.3 g Polyunsaturated Fat; 0.2 g Monounsaturated Fat; 69 mg Cholesterol; 54 mg Sodium; 14 g Total Carbohydrate; 2.5 g Dietary Fiber; 25 g Protein; 2.9 mg Iron; 575 mg Potassium; 7.3 mg NE Niacin; 0.6 mg Vitamin B6; 1.3 mcg Vitamin B12; 4.5 mg Zinc; 25.2 mcg Selenium; 104.7 mg Choline;