Soy-Ginger Steak or Portobello Mushroom Sandwiches - The Scramble

Ingredients

• 1/4 cup reduced-sodium soy sauce (or use any variety, use wheat/gluten-free, if needed)
• 1 Tbsp. rice vinegar or rice wine vinegar
• 1 clove garlic (minced, about 1/2 tsp.)
• 1 tsp. fresh ginger (peeled and minced)
• 1 tsp. brown sugar
• 1/4 tsp. black pepper
• 1 lb. boneless steak or portobello mushroom (thinly sliced if using mushrooms)
• 1/2 Tbsp. canola, vegetable, or olive oil
• 4 ciabatta or sourdough rolls (use wheat/gluten-free, if needed)
• 2 Tbsp. mayonnaise (optional)
• 4 leaves romaine or other crunchy lettuce (optional)
• 1/2 cucumber (thinly sliced (optional))
• 4 radishes (thinly sliced (optional))