For the salad: Boil the potatoes in salted water until fork tender, 10 to 12 minutes, then drain. Cook the pasta to al dente according to the package directions, then drain. Set the potatoes and pasta aside to cool slightly.
When cool, mix together the potatoes, pasta, basil, parsley, bell peppers and onion in a large bowl.
For the dressing: Whisk together the oil, vinegar, mustard, sugar, garlic and lemon juice in a small bowl. Season with salt and pepper.
Drizzle the dressing over the salad and toss until well incorporated. Taste and adjust the seasoning. Serve chilled or at room temperature in mason jars.