Make the candied walnuts by heating up a small pan and adding the walnuts, butter, sugar, water, and salt. Combine the mayonnaise, sweetened condensed milk, soy sauce, rice vinegar, and honey in a bowl and whisk until the ingredients are combined. Place the cornstarch in a bowl and add the shrimp. Toss the shrimp until they are evenly coated and transfer them to a plate. Heat up 2 tablespoons of oil in a skillet and when the oil is hot, add the shrimp, making sure not to overcrowd the pan. Add the cooked shrimp to the sauce and add the walnuts too. Toss the shrimp and walnuts until they are evenly coated and serve them over shredded cabbage and with a side of rice.