Method
To make Onion Marmalade, saute onions in oil in a large saucepan over medium-low heat 1 hour or until very tender, stirring occasionally. Stir in sugar, vinegar, Worcestershire, salt, pepper, and ground cloves. Cook over low heat, stirring occasionally 25-30 minutes or until liquid evaporates. Cool completely.
Refrigerate in a tightly covered container up to 1 week.
To assemble sandwiches, bring onion mixture to room temperature. Place endive or lettuce leaves on bottom halves of toasted rolls. Arrange beef over endive. Spread onion mixture evenly over beef. Place top halves on rolls. Cut each sandwich in half.
Photo and Recipe Courtesy of The Texas Beef Council.