Whisk eggs, 1/2 teaspoon salt, and 1/4 teaspoon pepper in a bowl until thoroughly combined, about 1 minute. Set aside
Cook bacon in a nonstick skillet over medium heat until crispy, about 10 minutes. Pour off all but 2 tablespoons fat from skillet. Add onion and jalapeno and cook until vegetables are softened and brown.
Reduce heat to low and add egg mixture and using a spatula, constantly and firmly scrape along bottom and sides of skillet until eggs begin to clump and spatula leaves a trail on the skillet.
Add spinach and continue folding egg mixture until it has clumped about 1 minute. Season with salt and pepper to taste.
Fill tortillas with egg mixture and serve immediately, with salsa, cheese, scallions, and limes (toppings optional)