In a large skillet or wok, heat 1 teaspoon of cooking oil over medium heat. Allow it to warm up for a minute.
Add 2 tablespoons of red curry paste to the skillet. Stir it in the hot oil for about 30 seconds, letting the aromas bloom and infuse the oil.
Pour in 1 tablespoon of fish sauce and give it a good stir to combine with the curry paste.
Slowly add in 12 ounces of coconut milk, stirring constantly to mix it well with the curry paste and fish sauce. Allow the mixture to come to a gentle simmer.
Add the red bell pepper strips and sliced mushrooms to the skillet. Let them cook in the simmering sauce for about 2-3 minutes until they are tender yet crisp.
Add 1/2 pound of uncooked, peeled shrimp to the skillet. Stir and cook for an additional 3-4 minutes, or until the shrimp turn pink and opaque.
(Optional) Tear 8 fresh basil leaves and sprinkle them over the curry just before serving for an aromatic touch.
Serve the curry over cooked rice in bowls, allowing the rice to soak up the delicious sauce.