Bring a large pot of water to a boil. Meanwhile, preheat a grill to medium high and line one side with foil. Pound the steak between 2 pieces of plastic wrap until 3/4 inch thick; cut in half lengthwise. Stir 1 tablespoon vegetable oil and the curry paste in a small bowl and spread all over the steak.
Add the rice noodles to the boiling water and cook as the label directs. Drain and rinse under cold water; shake off the excess water. Snip the noodles into pieces with kitchen shears.
Brush the uncovered side of the grill with vegetable oil. Toss the bell peppers and green beans with 1 tablespoon vegetable oil, 1/2 teaspoon salt and a few grinds of pepper and place on the foil. Grill the vegetables, stirring, until charred, about 10 minutes. Meanwhile, season the steak with salt and pepper and cook on the other side of the grill until marked, 4 to 5 minutes per side for medium rare; transfer to a cutting board. Chop the vegetables.
Whisk the remaining 3 tablespoons vegetable oil with the lime juice, brown sugar, fish sauce, chili-garlic sauce and 2 tablespoons water in a large bowl. Add the rice noodles, vegetables and basil; season with salt and pepper and toss. Divide among plates. Thinly slice the steak and add to the plates.