1.For caper aïoli, combine ingredients in a bowl, season to taste and set aside.
2.Combine flathead in a large bowl with spices and lemon rind, season to taste and toss to coat well. Heat olive oil in a large frying pan over medium-high heat, add flathead and fry, turning occasionally, until browned and just cooked through (3-4 minutes). Dress with a little lemon juice and divide among plates.
3.Toss remaining ingredients in a bowl to combine, season to taste and serve with flathead and caper aïoli.