Toast the bread. Spread one side of one slice with the pesto. In a small bowl, stir together the mayo and Sriracha (add Sriracha slowly to your heat preference). Spread this mayo on one side of the other slice of bread.
Gently press the baby spinach on top of the mayo. Add avocado, red onion strips, and then sprinkle feta cheese on top and gently press it in. Add the thinly sliced tomatoes on top along with a tiny sprinkle of salt and pepper. Add the well-drained red pepper strips on top. Place the sandwich piece with pesto on top. Gently press together. Cut with a sharp serrated knife and enjoy immediately!
Video
Notes
Note 1: You can buy jars of roasted red peppers at the store; they are usually near items like pickles, capers, and artichoke hearts. I love the soft texture and smoky flavor of roasted red peppers in this sandwich! Make sure to drain them thoroughly before adding to the sandwich or they will water down the bread.