Pat dry shrimp. Heat a large skillet with 1-2 tablespoons vegetable oil over medium-high heat. Sauté shrimp until pink and opaque, about 2-3 minutes. Remove and set aside. In the same skillet, add another tablespoon of oil and cook diced chicken breast until browned and cooked through, about 5-7 minutes. Transfer to a plate. Add another tablespoon of oil and cook diced pork until browned and cooked through, about 6-8 minutes. Transfer to the plate. If eggs are not already hard-boiled, boil eggs until hard, then cool, peel and halve.

Make the sweet and sour sauce

Combine and thicken sauce

In a small saucepan, whisk together pineapple juice, rice vinegar, ketchup, and sugar. Bring to a gentle simmer over medium heat. In a small bowl, whisk cornstarch with water until smooth, then whisk into the sauce. Cook, stirring, until the sauce thickens to a glossy consistency. Remove from heat.

Prepare greens and assemble

Prepare greens and toppings

Rinse and thoroughly dry the lettuce leaves. Tear into bite-sized pieces and arrange on a platter. Arrange tomato wedges and cucumber slices on the platter.

Assemble and serve

Assemble

Arrange shrimp, chicken, pork, and halved eggs over the greens. Drizzle or spoon warm sweet and sour sauce over the protein and vegetables, or serve sauce on the side. Garnish as desired and serve immediately.