Peel and devein the shrimp; wash them and pat them dry.
Peel the cucumber and cut it crosswise into 1/2-inch-thick rounds.
Peel 7 of the shallots and chop them very finely; peel and finely slice the remaining shallots.
Peel the garlic cloves; chop 4 of them very finely and cut the other 2 into fine slivers.
Combine the sliced shallots and slivered garlic and set these aside.
In a medium-sized pan combine the chopped shallots, chopped garlic, ground coriander, ground fennel (if you cannot get ground fennel seeds, simply grind whole seeds in a clean coffee grinder or food processor), white pepper, ground cumin, turmeric and 2 1/2 cups water.
Crumble in the red chilies; if you like mild to medium spicy food, you might consider leaving the chilies whole instead: this is what I did for my wife, who cannot easy as spicy food as I can, and she said it was perfect for her tastes.
Stir and bring to a boil; boil, uncovered, on a medium heat for about 5 minutes.
Add the cucumber rounds, stir and bring to a simmer; cover and simmer gently for 5 minutes.
Then add the shrimp, salt and sugar; bring to a simmer again and simmer gently for about 1 minute, stirring the shrimps around in the sauce.
Give the coconut milk a good stir and pour it in.
Bring the mixture to a boil, then lower the heat and simmer for 1 minute, stirring now and then.
Put the oil in a very small pan or small frying pan and set it over a medium-high heat; when the oil is hot, put in the slivered shallots and garlic.
Stir and fry until they turn a golden color.
Add the whole fennel seeds; stir once and quickly pour the contents of the pan (oil and sesasoning) into the pan containing the curry.
Cover the curry pan immediately to trap all the aromas.