Wrap the outside of a 9-inch springform pan tightly with two layers of heavy-duty foil.

Preheat oven to 325°F (165°C).

Mix graham cracker crumbs, sugar, and salt in a bowl.

Stir in melted butter until mixture resembles wet sand.

Press mixture firmly into bottom of pan.

Bake crust for 10 minutes and cool completely.

Heat guava paste, water, and lime juice in a saucepan over low heat until smooth.

Cool guava mixture to room temperature.

Beat cream cheese on medium speed for 3–4 minutes until smooth.

Add sugar and flour; beat until combined.

Add sour cream, vanilla, lime juice, lime zest, and salt; mix until smooth.

Add eggs and egg yolk one at a time on low speed just until incorporated.

Pour half of the batter over cooled crust.

Drizzle half of the guava mixture and gently swirl with a toothpick.

Pour remaining batter on top.

Drizzle remaining guava mixture and swirl gently.

Place pan in a roasting pan filled halfway with hot water.

Bake for 65–75 minutes until edges are set and center slightly jiggles.

Turn off oven and crack door open; let cheesecake cool inside for 1 hour.

Remove from water bath and cool to room temperature.

Refrigerate for at least 8 hours or overnight.

Remove springform ring, slice with a hot knife, and garnish if desired.