Combine water, lime juice, and coconut milk in a small pot over medium-high heat.
Once mixture starts to simmer, stir in sugar and salt.
Lower the heat to low and add rice. Stir, cover, and cook until rice is done. Remember to stir rice occasionally and break up the clumps.
Once rice is cooked, take off heat right away.
Shrimp:
In a small mixing bowl, combine coconut milk, lime juice, lime zest, sugar, salt and if using, cayenne pepper powder. Mix well and add shrimp. Stir well and let it sit while preheating the pan.
Preheat a cooking pan over medium-high heat.
Add a little bit of canola oil to the pan. Take out the shrimp and sear on both sides until opaque.
Add the coconut mixture that shrimp marinated in to the pan. Let it simmer for a minute or two. Take off heat.
Divide rice among two bowls and top it off with shrimp and sauce.