Cook your rice if you haven’t already (instructions below).
Preheat the oven to 300F.
In a large (12”) cast-iron or oven-proof skillet over medium-high heat, warm the olive oil. Add the mushrooms and salt. Cook for 7-8 minutes or until the mushrooms are cooked through and browned in spots, stirring every 2 minutes.
Meanwhile, in a large bowl, whisk together the eggs, 1 tablespoon soy sauce, and ginger until totally smooth and the eggs begin to look frothy.
In the skillet, add the remaining 1 tablespoon soy sauce and scallions and cook for 1-2 more minutes or until fragrant and scallions soften a bit, stirring often. Turn off the heat and spread everything out evenly in the pan.
Give the eggs one more whisk, then pour into the pan, distributing it all around. Use a wooden spoon or spatula to evenly distribute the veggies in the frittata.
Transfer to the oven and bake for 20-25 minutes, or until the eggs are mostly set and no longer jiggly in the center. Let the frittata rest for 10 minutes to finish cooking through and cool off.
To your warm rice, add in the cilantro, oil, zest + juice, and salt. Use a fork to fluff and mix everything until combined.
To make the cucumbers (if using), add all ingredients to a medium bowl and mix to combine. Let sit for at least 10 minutes, but overnight is best.
Use a knife to loosen the edges of the frittata. The first slice is always tricky to get out (a fish spatula works great here). Slice it up and serve warm with a side of rice and top with more cilantro, squeeze of lime, and sriracha (if using).