In a medium bowl, whisk shallot, garlic, red pepper flakes, and vinegar together. Slowly drizzle in 1/4 cup olive oil, whisking constantly until smooth. Mix in basil and parsley and season with salt and pepper to taste. Store chimichurri sauce in refrigerator until ready to use.
Place potatoes in a medium pot, cover with water, and lightly salt. Bring potatoes to a simmer over medium-high heat, then reduce heat to medium-low and allow potatoes to simmer 8-10 minutes until potatoes are crisp-tender (a paring knife should go through potatoes with a bit of resistance).
Drain potatoes and immediately plunge into a bowl of ice water to stop the cooking process. Once potatoes are cooled, drain well, arrange potatoes on a sheet pan, and pat dry.
Toss potatoes with remaining 1 tablespoon olive oil and salt and pepper to taste until evenly coated. Grease the grill grates of an outdoor grill well and preheat to 400F OR prepare a large skillet to use indoors on stovetop by greasing well.
Place potato cubes in a single layer on grill grates or work in batches to cook on stovetop. Turn potatoes occasionally until slightly charred and tender, about 6-8 minutes of cooking. Transfer to a large serving bowl.
Drizzle chimichurri sauce over potatoes and toss to evenly coat. Season potatoes with additional salt and pepper to taste if needed and serve warm. Enjoy!