Spread the bread in a single layer on a baking sheet, and toast until just golden brown, about 10 minutes. Set aside to cool.
Prepare the vinaigrette by whisking together the lemon juice, lemon zest, olive oil, thyme, and salt and pepper.
In a large bowl, toss together the haricots verts, cherry tomatoes, olives, anchovies, arugula, basil, parsley, and the lemon-thyme vinaigrette. Then, add the tuna and bread croutons to the bowl, and gently toss until everything is combined.
Let sit on the counter for at least 20 minutes before serving.