In a large bowl combine the drained beans, drained artichoke hearts, and sweet pepper strips. Set aside.
For dressing, in a screw-top jar combine oil, vinegar, honey mustard, salt, and cayenne pepper. Cover and shake well. Pour dressing over bean mixture. Stir gently to coat. Cover and chill for 6 to 24 hours, stirring once or twice.
To serve, spoon vegetables and marinade over romaine; sprinkle with walnuts. Makes 6 side-dish servings.