l large loaf ciabatta bread, halved horizontally
Heat 1 tablespoon oil in a skillet and sauté the onion for 4 minutes. Reduce heat and cook for 8 minutes longer or until golden brown. Cool.
Put the onion in the food processor with the parsley, salt, vinegar cilantro, oregano, lemon juice, garlic and seasonings. Process until finely chopped. Gradually add 5 tablespoons of the oil and process until well blended.
Brush the bread with the remaining oil and grill, cut sides down, until browned. Brush with the chimichurri sauce and serve warm.