Drizzle endives and radicchio with 1 tbsp (15 mL) of the oil; place on a greased grill over medium-high heat. Grill, covered and turning once or twice, until lightly charred, tender and slightly wilted, 4 to 6 minutes.
Transfer endives and radicchio to a cutting board; discarding any cores or root ends, coarsely chop into large bite-size pieces. Toss with half of the vinegar and half each of the salt and pepper; arrange on a large platter.
Toss mushroom caps, zucchini and red and yellow peppers with remaining 2 tbsp (25 mL) oil; place on greased grill over medium-high heat. Grill, covered and turning once or twice, until lightly charred and tender, 6 to 8 minutes.
Transfer to cutting board; coarsely chop vegetables into large bite-size pieces. Toss with remaining vinegar, salt and pepper; arrange on top of radicchio mixture. Sprinkle with basil.
Per serving (each of 8): 102 calories, 4 g protein, 6 g fat (1 g saturated fat), 11 g carbohydrates, 3 g fibre, 0 mg cholesterol, 180 mg sodium