Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the sweet potato into 1/2-inch thick rounds. Toss them with 1 teaspoon of olive oil and a pinch of sea salt.
Arrange the sweet potato rounds on the baking sheet and roast for 20-25 minutes, flipping halfway through, until tender and golden brown.
While the potatoes roast, season the chicken breast on both sides with sea salt, black pepper, and garlic powder.
Heat the remaining 1 teaspoon of olive oil in a skillet over medium-high heat. Add the chicken and sear for 6-8 minutes per side until the internal temperature reaches 165°F.
In a small bowl, whisk together the Dijon mustard and honey until smooth.
Once the chicken is cooked, let it rest for 5 minutes before slicing it into thick strips.
Assemble your sandwiches by using two large sweet potato rounds as the 'bun.' Layer with arugula, tomato slices, chicken strips, and a generous drizzle of the honey-mustard sauce.