1 7- to 8-ounce red bell pepper, cut into 1-inch pieces
1/2 cup mayonnaise
1 tablespoon finely chopped fresh chives
2 teaspoons fresh lemon juice
Large pinch of cayenne pepper
1/2 cup all purpose flour
1 teaspoon salt
1/2 teaspoon coarsely ground black pepper
1 large egg
2 tablespoons milk
2 1/2 to 3 cups fresh breadcrumbs made from crustless French bread
4 5- to 6-ounce skinless thin fish fillets (such as flounder or petrale sole)
2 tablespoons (or more) butter
2 tablespoons (or more) olive oil
Using on/off turns, chop bell pepper in processor until juices form. Transfer to small sieve set over bowl; let drain 10 minutes. Mix next 4 ingredients in small bowl. Stir in 1/2 cup bell pepper. Season mayonnaise with salt and pepper. DO AHEAD: Can be made 1 day ahead. Cover and chill.
Mix flour and next 2 ingredients in pie dish. Whisk egg and milk in another dish. Place breadcrumbs in third dish. Sprinkle fillets with salt and pepper. Coat each side with flour, then egg mixture, then breadcrumbs, covering completely.
Melt 2 tablespoons butter with 2 tablespoons oil in heavy large skillet over medium-high heat. Working in batches if necessary, add fish to skillet. Saut