Soak anchovies 10 minutes in cold water and pat dry with paper towels. Place in a large mortar or heavy bowl with the garlic and tomato paste. Pound with a pestle, wooden masher or spoon into a very smooth puree, or use food processor with steel blade.
Dribble the oil in, a few drops at a time, stirring constantly until thick and smooth, like mayonnaise. Stir in lemon juice and a few grounds of black pepper. Preheat oven to 500 F. Brown bread lightly on one side.
While bread is warm, spread untoasted side with anchovy mixture, pressing it into bread with back of fork or spoon. Bake for 10 minutes.
Sprinkle with parsley and serve at once.
Note: For a first course, use whole slices of French bread spread with anchovy mixture.