Line a baking sheet with parchment paper and place the sweet potato rounds on the baking sheet.
Add coconut oil, a pinch of sea salt and freshly ground black pepper and toss to combine.
Roast for 15 minutes until tender.
Remove from the oven and set aside to cool.
Drain the sunflower seeds and almonds, place them in the food processor together with the lime juice, cucumber, water, sea salt, parsley leaves and black pepper, and pulse to obtain a smooth cream.
Spread the tzatziki sauce on a whole wheat toast slice, add roasted sweet potato rounds and fresh greens and top with another toast slice.