Rinse the cilantro roots to remove any soil. Peel the garlic and ginger. Cut off the tips of the chili. Set aside the cilantro leaves. Roughly chop everything.
Transfer to a mortar and pestle and grind until you have a paste. Alternatively, use a food processor.
Heat the cooking oil in a pan. Add the paste. Heat gently until fragrant.
Add the tilapia fillets to the pan. Cook for about a minute then carefully turn over and cook for another 30 seconds.
Pour in the coconut cream. Season with fish sauce or salt. Stir gently. Cook just until the sauce simmers.
To serve, place the tilapia fillet over hot rice. Spoon some of the sauce around it.
Chop the reserved cilantro leaves and sprinkle over the tilapia. If you want extra spice, thinly slice a chili and sprinkle over the fish along with the cilantro leaves.