Artichoke-mushroom frittata with apple and arugula salad

• Cut the mushrooms into quarters. 
• Crack the eggs into a medium bowl and season with salt and pepper. Using a fork or whisk, lightly beat until just blended. 

In a medium [large] frying pan over medium-high heat, warm 1 to 2 tablespoons oil until hot but not smoking. Add the mushrooms and artichoke hearts and cook, stirring once or twice, until just starting to brown, 2 to 3 minutes. Working in batches if needed, stir in the spinach, season with salt and pepper, and cook until just wilted, 1 to 2 minutes. 

Spread the vegetables evenly over the bottom of the pan. Pour the eggs on top. Reduce the heat to medium-low, cover, and cook without stirring until the eggs are set, 3 to 5 minutes. Remove from the heat and let cool for 5 minutes, then cut into wedges.

While the frittata is cooking and cooling, prepare the salad.

• Core and cut the apple into ¼-inch-thick slices.
• Working over a small bowl, zest and juice the lemon. [Zest both lemons; juice 1 lemon. Save the remaining zested lemon for another use.]

To the bowl with the lemon zest and juice, stir in 1 to 2 tablespoons oil; season to taste with salt and pepper. 

In a medium bowl, toss together the apple and arugula with as much of the lemon vinaigrette as you like (set aside any remaining vinaigrette for serving). Season to taste with salt and pepper. 

Transfer the apple and arugula salad to individual plates. Spoon the artichoke romesco onto the plates and top with the frittata wedges. Serve any remaining lemon vinaigrette on the side.