Season the chicken breast evenly with half of the sea salt and black pepper.
Heat 1 teaspoon of olive oil in a medium skillet over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
While the chicken cooks, cut the sourdough bread into 1-inch cubes and toss them in a small bowl with 1 teaspoon of olive oil and half of the garlic powder.
Place the bread cubes in a separate small skillet over medium heat, tossing frequently for 4-5 minutes until they are golden brown and crunchy.
In a small mixing bowl, whisk together the Greek yogurt, Dijon mustard, lemon juice, Parmesan cheese, remaining garlic powder, salt, and pepper until smooth.
Wash and chop the romaine lettuce into bite-sized pieces, then place them in a large salad bowl and toss thoroughly with the yogurt dressing.
Slice the cooked chicken breast into strips and arrange them over the dressed greens, finishing with a topping of warm garlic croutons.