For basting sauce: With a piece of wax paper, mash garlic and salt with a fork until well blended. Place in a small bowl. Whisk in balsamic vinegar, olive oil and pepper; set aside.
Core, seed and cut bell peppers into thirds. Brush both sides of peppers with sauce and place in large bowl. Pour remaining sauce over top.
Remove peppers from sauce; reserving sauce. Place peppers skin side down on greased barbecue rack over medium high heat for 6 - 8 minutes or until lightly charred but not mushy, basting with sauce and turning every three minutes. Slice peppers into wide strips. Arrange on a platter, alternating colors. Season with salt and pepper. Sprinkle with fresh herbs, feta and olives. Drizzle the one tablespoon balsamic vinegar over peppers.