Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the russet potato into thin wedges and place them in a mixing bowl.
Toss the potato wedges with 1 teaspoon of avocado oil, the dried rosemary, and half of the sea salt and black pepper.
Spread the fries in a single layer on the baking sheet and roast for 20-25 minutes, turning halfway through, until golden and crisp.
Season the chicken breast evenly with the garlic powder and the remaining sea salt and black pepper.
Heat the remaining teaspoon of avocado oil in a medium skillet over medium-high heat.
Add the chicken breast to the skillet and sear for 5-6 minutes per side until the internal temperature reaches 165°F and the outside is nicely browned.
During the last minute of cooking, place the sprouted grain bun halves in the skillet or a toaster to lightly brown.
Spread the Dijon mustard on the bottom bun, then layer with arugula, the tomato slice, and the pan-seared chicken.
Top with the remaining bun half and serve immediately alongside the hot herb fries.