Lightly toast the slice of cassava or coconut flour bread until crispy. Set aside.
Heat the olive oil in a skillet over medium heat. Add the minced garlic and cook for about 1 minute until fragrant.
Add the sliced shiitake mushrooms to the skillet and cook until they are tender and browned, about 5-7 minutes.
Stir in the dried thyme, dried oregano, and sea salt. Continue to cook for another 1-2 minutes, allowing the flavors to meld.
In a bowl, lightly toss the arugula with a small drizzle of olive oil and a pinch of sea salt. This will help the arugula stay fresh and vibrant.
Spread the sautéed mushrooms evenly over the toasted bread. Top with the seasoned arugula.
Serve immediately while the bread is still crisp and the arugula is fresh.