1. Light the grill or heat the broiler. Using 4 1/2 tablespoons of the oil, brush both sides of each slice of bread. Sprinkle both sides with the table salt. Grill or broil the bread, turning once, until crisp and golden on the surface but still soft inside, about 4 minutes in all.
2. Rub the sardines all over with the remaining 1 1/2 tablespoons oil and sprinkle with the coarse salt. Grill or broil the sardines for 4 minutes. Turn and cook until golden brown and just done, about 3 minutes. To serve, top each piece of grilled bread with 4 sardines.
Fish Alternatives: Sweeter than sardines, smelts are an ideal alternative here. They're usually smaller, so cook them a little less.
Wine Recommendation: The saltiness of the sardines and the rusticity of this dish are perfect with a very cold bottle of unassuming and refreshing vinho verde from Portugal. Many vinho verdes are nonvintage, but if those available to you are dated, choose as young a bottle as possible.