1 cup fresh basil leaves, loosely packed
2 to 2 ½ cups olive oil
4 egg yolks
salt and freshly ground pepper
1 to 1 ½ Tbsp. fresh lemon juice
Blanch the basil leaves in boiling water for three seconds; immediately drain them and drop them into cold water to stop the cooking. Pat the leaves dry with paper towels and chop them fine. Combine the basil and egg yolks in a warmed bowl. Whisk them vigorously for a minute, add 1 Tbs. of the lemon juice and whisk until well mixed.
Whisking constantly, add the oil drop by drop. When the sauce starts to thicken, add the oil in a thin steady stream, whisking rhythmically, until the mayonnaise reaches  the desired consistency. Season to taste with salt, pepper and additional lemon juice.
Serve with grilled fish steaks or as a dip for artichoke leaves. Makes 3 cups.
(The Good Cook- Outdoor Cooking by the editors at Time-Life, 1983)