Bring a large pot of salted water to a boil and cook the noodles according to package instructions. Reserve about 1½ cups of pasta water before draining. Set the cooked noodles aside while you prepare the other ingredients.
Heat one tablespoon of avocado oil in a large skillet over medium-high heat. Pat the shrimp dry and season lightly with salt and pepper. Cook for 2 to 3 minutes per side until pink and fully cooked, then transfer to a bowl.
Add the remaining oil to the same skillet. Toss in the snap peas, sliced peppers, and shallot. Stir-fry for 3 to 4 minutes until slightly charred but still crisp.
Reduce the heat slightly and add the garlic and grated ginger. Cook for about 30 seconds while stirring constantly. The mixture should become fragrant without browning.
Pour in the coconut milk and whisk in the peanut butter and brown sugar. Slowly add reserved pasta water until the sauce becomes creamy and smooth. Continue whisking until fully combined.
Stir in the fish sauce, lime juice, and sriracha. Taste the sauce and adjust seasoning if needed. The sauce should be creamy, slightly sweet, tangy, and savory.
Return the shrimp and vegetables to the skillet. Add the cooked noodles and toss until every ingredient is coated in the peanut sauce. Add more pasta water if the sauce becomes too thick.
Fold in the crushed peanuts, sliced green onions, and chopped basil just before serving. This keeps the garnishes fresh and crunchy. Serve immediately while warm.