• Wash the spinach and put it in a large salad bowl.
• In a medium skillet, heat 1 tablespoon of olive oil over medium-high heat. Add the potatoes and cook, stirring once or twice, until they begin to brown, about 5-8 minutes. Reduce heat to low and cook another 4-5 minutes, or until the potatoes are tender and cooked through. Add the onion and green beans to the pan; cook 5 minutes. Pour the warm vegetables onto the spinach. Let the salad sit while you make the vinaigrette (the spinach will wilt very slightly.)
• Add half the tomatoes, feta, olives, and half of the basil vinaigrette. Toss to combine. Serve the salad with the remaining vinaigrette.

To make the basil vinaigrette:

• Add the vinegar, lemon juice, mustard, garlic, and basil to a blender. Cover and blend on medium speed for about 5 seconds (just to break up the basil). With the blender running, drizzle in the olive oil. Blend until the dressing is smooth, 15-20 seconds. Season to taste with salt and pepper.