Start by heating your wok or skillet over high heat until shimmering, then add the oil and swirl to coat the surface.
Add the crushed garlic and sliced chilies to the hot oil. Cook for about 15-20 seconds, until fragrant and slightly blistered, with a smoky aroma filling the air.
Quickly toss in the shrimp, spreading them out in a single layer. Cook for 2-3 minutes, stirring constantly, until they turn pink and opaque with a slight jiggle in the center.
Pour in the fish sauce and oyster sauce, stirring briskly to coat the shrimp evenly and create a glossy, flavorful glaze.
Add the torn basil leaves to the pan, tossing vigorously for about 10-15 seconds until wilted and fragrant, but still vibrant green.
Taste the dish and adjust the seasoning if needed. Remove from heat immediately to prevent basil from turning bitter.
Serve the hot, fragrant stir-fry immediately, garnished with extra basil if desired, alongside steamed rice or on its own.