In a food processor or blender pulse the vinegar, olives, mustard and thyme. Slowly add 1/2 cup olive oil and 3 tablespoons water while continually blending until you have a loose dressing. Add to
In a large non-stick skillet over high heat add the remaining 2 tablespoons of olive oil and then add the diced potatoes sprinkled with 1 teaspoon salt and 1/2 teaspoon pepper.
Cook stirring occaisionally until you have crisp and golden browned potatoes approximately 5 minutes. Reduce heat to medium and cook until pieces are tender - another 5 minutes. Stir in red onion and cook a final 5 minutes stirring and watching closely. Set aside on a paper towel lined plate.
Portion arugula on dinner plates or on a large serving plater. Top with the potato mixture, feta and tomatoes. Drizzle with vinaigrette - you may have some leftover.