Open a can of coconut milk (do not shake with the can prior to opening it), a thick mass should be at the top (coconut cream), and thin liquid at the bottom (coconut water). Spoon out about 2/3 of the cream, add to a large pot, heat over medium heat until bubbling and oil begins to separate from the cream (if this is not happening, just continue with the recipe).
Add the red curry paste, garlic, ginger and lemongrass to the pot and cook over medium heat for about 2 minutes or until fragrant.
Add the cubed pumpkin, cook for a minute.
Pour in the remaining coconut milk and broth, cook for another 10 minutes over medium-low heat, or until the pumpkin is tender (cooking time depends on the type of pumpkin and how big the pieces are, adjust accordingly).
Poach the shrimp: Set your heat to the minimum - the curry should be very hot and steaming, but it should not be boiling. Add shrimps to the pot, then take the pot off the heat. Leave for a couple of minutes (about 3 minutes), stirring from time to time (shrimps should be submerged in the broth). You can take one shrimp out and cut it in half to see if it's cooked through (it will be white/pink in the middle instead of grey/translucent).
Add the spinach and stir the curry until the leaves are wilted.
Season your curry: add finely crushed palm sugar, fish sauce and tamarind paste to taste. If the curry is not salty enough - add more fish sauce, not sour enough – tamarind paste, not sweet enough - more sugar.
Serve with rice and sprinkle with fresh coriander leaves.