Prepare Chilli-Garlic Paste: Using a mortar and pestle, crush the garlic, 2 bird’s eye chillies, and the large red chilli (diced). Pound into a paste—it can remain a little chunky.
Make Prik Nam Pla Dipping Sauce: Mix together the lime juice, 2 bird’s eye chillies (finely sliced), 1 tablespoon fish sauce, and ½ teaspoon sugar. Set aside for later.
Stir-Fry Beef: Heat a wok or large frying pan over high heat. Once hot, add 1 tablespoon of oil. When the oil is hot, add the beef and stir-fry for 2-3 minutes.
Add Chilli-Garlic Paste and Seasonings: Add the chilli-garlic paste to the beef, stir quickly, then add the fish sauce and sugar. Continue to cook for another 2 minutes, adding water 1 tablespoon at a time if the mixture begins to dry out.
Finish with Basil: In the last 30 seconds of cooking, add the basil and toss. Then remove from the wok.
Serve: Serve the beef alongside steamed jasmine rice, with the Prik Nam dipping sauce and a crispy fried egg on top.