Here is my recipe without using the ice cream machine:
Red Guava Ice Cream
Makes about just under 1L of ice cream.

Red Guava Ice Cream
Ingredients:
600ml of good quality custard or you can make your own ice cream base (recipe below)
250gr of guava paste diluted in 30ml of warm water, the red guava paste can be found in any Portuguese shop.
1 can of red guava – blended and sieved
Method:
Start with preparing the custard in advance – homemade recipe below
1.Blend the canned guava and sieve them.
2.Mix the sieved guava and the custard
3.Leave in the freezer for 3 hours
4.In the meantime place the 250gr guava paste in a pan with water, dilute it and let it cool. 5.Now take the ice cream out of the freezer and mix well with a fork and blend the diluted guava paste with the guava ice cream making swirls.
6.Put back in the freezer overnight.
Leave out of the freezer for 10 mins before serving.
Making your own ice cream base (custard):
Ice cream base:
1 cup whole milk
4 large egg yolks
3/4 cup sugar
2 cups double cream
Heat the milk in a sauce pan over medium-low heat.
Prepare an ice bath by setting medium bowl , enough to hold 2 litres of liquid, over a larger bowl partially filled with ice water.
Set a strainer over the smaller bowl and set aside.
In a separate bowl, whisk together the egg yolks and sugar until pale yellow in color and the sugar has dissolved. Gradually pour the warmed milk into the yolk mixture, whisking constantly. Pour the mixture back into the same saucepan you used to warm the milk. Cook for 3 to 5 minutes, stirring constantly, until the custard thickens and coats the back of a wooden spoon.
Strain the custard into the top bowl of the ice bath to stop the cooking process. Add the double cream and stir over the ice bath until cool. Cover the mixture itself with plastic wrap tightly and chill thoroughly, preferably overnight. Yield: about 3 cups or 600ml

Delicious and creamy red guava ice cream