Preheat the broiler. Position a rack about 4 inches from the heat source. Place the peppers on a baking sheet on the rack and char, turning frequently, until blackened on all sides, 6 to 8 minutes. Transfer the peppers to a bowl, cover with plastic wrap, and let sit for 15 to 20 minutes. When cool, peel off the pepper skins and discard the skins and seeds. Slice the peppers into strips and place them in a bowl. Add the garlic, oil, lemon zest and juice, vinegar, and salt and mix well. Season to taste with salt. Garnish with more lemon zest.