Drain the tomatoes in a sieve to remove excess liquid while you prepare the rest of the ingredients.
In a bowl, combine the tomatoes, onion, garlic, olive oil, lemon juice, basil, tarragon, salt, and pepper. Add the croutons and toss well.
Divide tomato mixture among 4 plates. Top each serving with an equal amount of the arugula. With a vegetable peeler, shave the Parmesan over the salad. Serve immediately.
Michael's Notes: I've used basil and tarragon here, but you can use any herbs you like. Parsley and marjoram come to mind as good alternatives.
Preheat oven to 375 degrees F and preheat a cookie sheet in it.
Melt the butter in a large skillet over medium heat and cook until it foams. Add the garlic and cook until fragrant, about 30 seconds to 1 minute. Add the bread cubes and toss to coat with the butter. Season with salt and pepper. Transfer the bread to a baking sheet. Immediately sprinkle with the cheese and toss again while warm to melt the cheese.
Bake, stirring once or twice, until the croutons are crisp and lightly colored on the outside but still soft within, about 8 or 9 minutes. Let cool. Store in an airtight container.
Michael's Notes: I use a serrated knife to remove the crust from day-old bread, then switch to a chef's knife to cut the cubes because it doesn't tear the bread. Also note that I recommend grating the Parmesan finely so that it will stick to the bread better.
Yield: about 6 cups