1/4 cup pine nuts, toasted (you could also use walnuts instead)
1/2 garlic clove, roughly chopped
juice and zest from 1/2 a lemon
1/4 cup olive oil (or more)
a few pinches of red pepper flakes
salt & pepper
Slice the peaches into 6 segments per peach. In a small bowl, toss peaches with olive oil, balsamic, and just a small pinch of salt.
Heat your grill (or grill pan) to medium high heat and brush it with some oil. Place the peach slices on the hot grill and cook each side for 2-3 minutes without moving them (near the end you can gently peek to see how your grill marks are coming along). When your peaches are grilled, set aside and allow them to cool to room temperature.
Meanwhile make the pesto. Combine all ingredients in a small food processor and pulse to combine. Add more oil for a smoother pesto, or leave it chunky - whichever consistency you prefer.
Toss the arugula with just a little bit of olive oil and a few pinches of salt. Assemble on a platter and top with mozzarella slices, peaches, dollops of pesto, and a few pinches of red pepper flakes. Squeeze just a bit of lemon on top and serve.