Combine lemon juice and zest, rosemary, and Aleppo in a small bowl.
Slowly whisk in the oils until emulsified.
Season to taste with sea salt and freshly-ground black pepper.
Combine the watermelon cubes and cherry tomatoes in a bowl.
Add 2 tablespoons of the vinaigrette and toss to coat.
Set aside for about 10 minutes to marinate.
Toss together the arugula, herbs, walnuts, and pecorino in a large serving bowl.
Add a pinch of sea salt.
Add the watermelon cubes and cherry tomatoes, draining off any excess liquid that's accumulated in the bottom of the bowl.
Add just enough additional vinaigrette to lightly coat the arugula and herbs, taking care to not overdress.
Toss lightly, and season to taste with sea salt, freshly -ground black pepper, and Aleppo for more heat.