• Prep everything before you heat the pan: mince the garlic, slice the chilies, chop the onion, and tear the basil.
• Heat a large skillet or wok over high heat. Add the oil and swirl until shimmering, then toss in the garlic and chilies. Sizzle for about 20–30 seconds until fragrant but not burnt.
• Increase the heat to medium-high and add the ground beef. Break it up with a spatula and cook until it’s no longer pink and begins to brown at the edges, about 4–6 minutes.
• Stir in the onion and cook until it’s softened and just starting to turn translucent, 1–2 minutes.
• Pour in the soy sauce, fish sauce, and oyster sauce (if using). Sprinkle in the sugar and toss everything to coat the meat. Cook for another 1–2 minutes until the flavors meld and the mixture looks glossy.
• Turn off the heat, add the torn Thai basil, and toss just until it wilts and releases its perfume.
• Taste and adjust: a quick squeeze of lime juice or a pinch more sugar can balance any overly salty notes. Serve hot.