Preheat the oven to 400°F (200°C). Peel and chop the sweet potatoes into 1-inch cubes and add them to a baking tray. Season with extra virgin olive oil and salt; toss to coat evenly. Bake for about 30 minutes until fork-tender.
Heat extra virgin olive oil in a non-stick or stainless steel pan over low heat. Add seeds and dried cranberries; season with a pinch of salt. Toast for about two minutes while stirring often. Set aside to cool.
In a mixing bowl, whisk together extra virgin olive oil, lemon juice, mustard, maple syrup, oregano, salt, and black pepper until well combined.
Arrange arugula on a large serving platter. Top with roasted sweet potatoes, sliced red onion, crumbled feta cheese, toasted seeds, and cranberries. Drizzle half of the dressing over the salad and serve with the remaining dressing on the side.