In a small bowl, whisk together the olive oil and balsamic vinegar. Set aside.
In a large bowl, layer 1/2 of your prepped salad ingredients in this order:- arugula- sliced red onion- chopped watermelon- sliced almonds- feta crumbles
Repeat the layers until all ingredients are used up. Store for later or plate the salad and drizzle each serving with balsamic dressing.