Preheat the oven to 350°F (175°C).

Mix the crushed pretzels, melted butter, and 3 tablespoons sugar together. Press the mixture into the bottom of a 9×13 inch baking dish and bake for 10 minutes. Let cool.

In a mixing bowl, beat together cream cheese and 1 cup sugar until smooth. Fold in the whipped topping. Spread the mixture evenly over the cooled crust.

In a separate bowl, dissolve the strawberry flavored Jell-O in boiling water. Mix in cold water and then stir in the sliced strawberries. Let the mixture set briefly until it begins to thicken, then pour over the cream cheese layer in the baking dish.

Refrigerate the salad until it sets, about 4 hours.