An herb- and chile-packed chimichurri sauce makes this meat-and-potatoes main vibrant and exciting. Double the mixture, and spoon over grilled steak or fish on another night. Use your microwave to jumpstart the potatoes, then crisp them up in the drippings from the cooked chicken thighs for maximum flavor. Fresno chiles have a medium heat, just slightly more mild than a jalapeño. You can use either here, or substitute a generous pinch of crushed red pepper in the chimichurri. Skinless, boneless thighs can vary widely in size. Shop by weight rather than count, cutting larger thighs in half if needed.
Place 2 tablespoons water and potatoes in a microwave-safe bowl; cover and microwave at HIGH 4 minutes or until almost tender.
Heat 2 tablespoons oil in a large nonstick skillet over medium-high. Sprinkle chicken with 1/2 teaspoon salt and 1/2 teaspoon black pepper. Add chicken to pan; cook 5 minutes on each side. Remove from pan; keep warm.
Cut half of chile into thin slices; finely chop remaining half. Add potatoes and chile slices to drippings in pan; cook 4 minutes. Stir in 1/4 teaspoon salt and 1/8 teaspoon black pepper.
Place chopped chile, parsley, cilantro, shallots, and garlic in a mini food processor; pulse to combine. Add remaining 3 tablespoons oil, 1/4 teaspoon salt, 1/8 teaspoon black pepper, and juice; process until smooth. Serve with chicken and potatoes.