1 In A Bowl, Dissolve Lime Jello And Salt In 2 Cups Of Hot Water (Don'T Use Boiling Water, Just Regular Hot Water). Add 2 Cups Cold Water. Chill Until Slightly Thickened - The Consistency Of Egg Whites, About 30 Minutes. 2 In A Separate Bowl Mix Cucumber, Horseradish, Grated Onion, And Vinegar. Fold Pineapple And Cucumber Mixture Into Jello. Pour Into A Jello Mold And Chill For Several Hours (About 6) Until Gelatin Sets. 3 To Remove Jello From Its Mold, Fill Up A Basin Half-Way With Hot Water. Lower The Jello Mold Into The Hot Water, Metal Side Down, Until The Water Comes Up Almost To The Edge Of The Mold. Keep It There 5 Seconds And Remove. Place A Plate On Top Of The Jello Mold And Turn Upside Down. The Jello Salad Should Just Slide Out.