To start, bring 3 cups water to boil, then reduce heat to simmer. Add lentils and cook uncovered, for about 20-25 minutes, or until lentils are chewable but still have a bit of "bite". When done, rinse lentils with cool water and drain. Set aside for later.
To make panzanella croutons, break your bread into small pieces, about an inch thick. You can use a knife but the traditional way is to break the bread by hand! I used two slices of Ezekiel bread and that turned out to be about 2 cups, when broken.
Bring a pan to medium heat. Drizzle pan with a generous glug of olive oil. Add in bread pieces and cook, tossing frequently, until bread starts to become toasty and brown, about 5-10 minutes depending on how hot your pan is.
When panzanella bread is done, toss in a bowl with a pinch of sea salt and pepper. Set aside.
To make the vinaigrette, combine all ingredients into a high speed blender and blend on high until herbs are fully emulsified and the dressing is smooth. Taste, and adjust seasonings if necessary.
To make the salad, toss a few handfuls of fresh arugula, lentils, panzanella bread, and dressing in a bowl until evenly mixed.