Select a medium-size souffle dish (6" diameter, 5 1/2 cups volume).

Prepare a foil collar: cut a 25" piece of nonstick aluminum foil, fold lengthwise with the nonstick side out.

Wrap the foil around the souffle dish with the folded edge up.

Press the ends together and fold twice to secure the foil collar tightly around the dish, extending about 3" above the rim.

Place gelatin in a small heatproof bowl.

Add boiling water and stir until gelatin is completely dissolved (2-3 minutes).

Let the gelatin mixture cool for 10 minutes.

Combine strawberries, sugar, lime juice, and tequila in a food processor.

Process until the mixture is pureed.

Pour the strawberry puree into a large bowl.

Stir the dissolved gelatin into the strawberry mixture until well combined.

Using a wire whisk, gently fold in the thawed whipped topping until no white streaks remain (approximately 2 minutes).

Pour the mousse mixture into the prepared souffle dish, smoothing the top.

Refrigerate for at least 6 hours, or preferably overnight, until the mousse is set.

To serve, carefully remove the foil collar.

Gently press sugar crystals onto the exposed sides of the mousse and garnish with lime slices and strawberries, if desired.