Puree the peeled and roughly chopped mango along with sugar. The puree should measure 1 1/2 cups. I used 3 small alphonso mangoes and 3/4 cup sugar.
Soak 5 grams agar agar in 1/2 cup water for 15 minutes. In another small soak soak 3 grams agar agar in 1/4 cup water for coconut layer.
keep a square tin ready for setting the jelly.
Heat the 5 grams agar agar soaking in 1/2 cup water. Whisk well and keep cooking low flame till agar agar dissolves completely and water turns clear.Once agar agar is dissolved, add the mango puree and whisk very well. Add lemon juice and mix well. You will see the whole mixture getting thick. Quickly pour into the tin you are setting the jelly. There will be some air bubbles, just prick them off. Let the mango layer set for 30-45 minutes.
Once the mango layer is well set, prepare the coconut layer. Heat the 3 grams agar agar soaking in 1/4 cup water till the agar agar is dissolved completely. Take off from heat and add the coconut milk. Pour this immediately over the mango layer and shake gently to level.
Let this completely set for 45 minutes. Once the mixture is well set and not shaky the mango coconut jelly is ready to serve. Cut and serve mango agar agar jelly as needed.