Saffron Aioli for Basque Salad

Put egg yolks, garlic, and saffron into a food processor; season with salt and pepper. Process until smooth. With processor running, gradually add oil, drop by drop at first, then in a slow, steady stream, until a thick mayonnaise forms. Mix in lemon juice. Transfer to a small dish. Serve at room temperature; do not leave unrefrigerated longer than 1 hour. Aioli can be refrigerated, covered, up to 2 days.