Light, airy, and citrusy—this Key lime mousse blends tangy flavor with creamy texture, creating a refreshing dessert perfect for warm days.

This chilled Key lime mousse is a delicious combination of sweet custard and zesty lime. Instead of milk or cream, the custard base is made with fresh Key lime juice, giving it a fragrant, sharp flavor. If Key limes aren’t available, regular limes work just as well.

Ingredients

• ¼ cup water
• 1 envelope unflavored gelatin (about 2 1/4 teaspoons)
• 1 ½ cups sugar, divided
• 4 teaspoons finely grated lime zest (from 5 Key limes or 2 regular limes), plus more for garnish
• 2/3 cup fresh lime juice (from 18–20 Key limes or 4–6 regular limes)
• ¼ teaspoon salt
• 6 large egg yolks or pasteurized egg yolks
• 7 large egg whites or pasteurized egg whites
• 1 ½ cups reduced-fat plain Greek yogurt

Directions

1. Prepare the gelatin: Sprinkle gelatin over water in a small heatproof bowl. Let soften for 3 minutes. Dissolve gently in a skillet of hot water or microwave briefly until clear. Set aside.
2. Make the lime custard: Process 1 cup sugar with lime zest in a food processor until fine. Place in a saucepan with lime juice and salt. Heat until hot and sugar is dissolved. Whisk yolks in a separate bowl, then slowly add the hot lime mixture while whisking constantly.
3. Cook and thicken: Return to the saucepan and cook over medium heat, whisking until the custard coats the back of a spoon (2–4 minutes). Transfer to a stand mixer bowl and beat until thick and pale, 3–5 minutes. Drizzle in the dissolved gelatin while mixing and continue until cooled to room temperature.

4. Beat egg whites: In a clean bowl, beat whites until foamy. Gradually add the remaining ½ cup sugar, a tablespoon at a time, beating until stiff peaks form.
5. Fold and combine: Gently whisk yogurt into the lime custard, then fold in the egg whites in three additions. Divide evenly among ten 8-ounce ramekins or spoon into a large 2 ½-quart dish.
6. Chill: Refrigerate until set, at least 3 hours or up to 24 hours. Garnish with lime zest before serving.

Tips

Make Ahead: Cover and refrigerate for up to 1 day. Garnish just before serving for best freshness.

Equipment: Ten 8-ounce ramekins or one 2 ½-quart soufflé dish.

Zest: Use a microplane or fine grater for best results. Avoid the white pith, which is bitter. For strips, use a peeler and slice finely.

Food Safety: Since the eggs are not cooked, use pasteurized eggs to reduce the risk of foodborne illness, especially for children, elderly individuals, or those with weakened immune systems.