A colorful and unusual first course.
4 medium leeks (white and pale green parts only)
4 teaspoons red wine vinegar
Char bell pepper over gas flame or under broiler until blackened n all sides.Seal in paper bag and let stand 10 minutes. Peel, seed and chop pepper.
Cut leeks in half lengthwise to within 1 inch of base, leaving base intact. Rinse leeks under running water. Add leeks to pot of boiling salted water; reduce heat and simmer until leeks are tender when pierced with knife, about 7 minutes. Drain; cool. Using paper towels, squeeze excess moisture from leeks. Cut leeks completely in half lengthwise. Cut off and discard roots. Cut leeks crosswise into 3-inch pieces. (Bell pepper and leeks can be prepared 1 day ahead. Cover separately; chill.)
Place leeks on platter. Whisk vinegar and mustard in bowl to blend. Gradually whisk in oil. Mix in bell pepper. Season with salt and pepper. Spoon dressing over leeks. Sprinkle cheese, walnuts and mint over.