In a heavy saucepan, add milk, a cinnamon stick, salt, and lime peel. Heat over medium-low, stirring regularly. Simmer for 7-10 minutes without boiling, then remove from heat to let the flavors steep.

In a small bowl, mix 2 tablespoons of the warm milk with cornstarch until smooth.

In a large bowl, beat the egg yolks with sugar until well combined.

Slowly pour ½ cup of the warm milk into the egg mixture at a time, stirring constantly. After adding half the milk, discard the cinnamon stick and lime peel.

Pour the egg mixture back into the saucepan with the rest of the milk and heat on medium-low.

Add the cornstarch mixture to the saucepan and stir continuously. The custard will thicken in about 10 minutes.

Once thickened, remove from heat and stir in vanilla extract. Pour the custard into individual bowls.

Cover with plastic wrap to prevent skin from forming, then refrigerate for 2 hours. Sprinkle with cinnamon before serving.