Begin by preparing the flat rice noodles according to the package instructions. Once cooked, drain them thoroughly and set aside to prevent sticking. Meanwhile, combine the soy sauce, oyster sauce, fish sauce, and sugar in a small bowl or jug, stirring until the sugar is fully dissolved to create a harmonious, flavorful sauce. Heat the vegetable oil in a large wok or frying pan over high heat until shimmering. Add the chopped garlic and birds-eye chillies, stir-frying briskly for around 20 seconds until fragrant and just beginning to turn golden — be careful not to burn the garlic as it can turn bitter. Next, add the sirloin steak, sliced thinly, and stir-fry for about one minute until the meat is nicely seared on the outside and begins to brown. Toss in the broccoli florets and stir-fry for another minute to keep them crisp and bright green. Then, add the cooked noodles and pour over the prepared sauce. Stir-fry everything together for a further 1 to 2 minutes, ensuring the noodles are evenly coated and the dish is piping hot. Finally, stir through the handful of fresh basil leaves, allowing their sweet aroma to infuse the dish as you turn off the heat. Serve the drunken noodles immediately to enjoy the vibrant flavors and textures at their best. For an extra touch, garnish with extra basil or a squeeze of lime if desired. Remember, avoid letting the noodles sit too long after cooking, as they can become soggy.