Pat shrimp completely dry. Season with salt and pepper. Heat oil in a wide skillet over high heat and add your butter. Add shrimp in a single layer and don't crowd.
Sear 60–90 seconds without touching until the underside is deep pink and caramelized. Remove shrimp immediately.
Build the Sauce
In the same pan over medium heat, add remaining butter. Add garlic and cook 30 seconds until fragrant. Add soy sauce, fish sauce, sugar, and stock. Stir to combine and bring to a simmer.
Finish the Noodles
Add egg noodles to the pan. Toss and press noodles into the sauce. Let simmer and reduce 2–3 minutes, tossing constantly.
Finish with scallions, sesame seeds, and a lime wedge on the side.
Notes
Pat shrimp bone dry before searing. Any moisture and you get steam instead of caramelization.
The lime isn't just garnish! A squeeze at the table cuts through the butter and brightens the whole bowl.
Don't overcook the shrimp. They go back in on the plate, and residual heat finishes them perfectly.