Preheat oven to 350°F.
Pulse together garlic, beans, half the lemon juice, 1 tablespoon olive oil, half the parmesan, and a pinch of salt and pepper in a food processor until smooth.
Toast each tortilla over a low gas flame, on a griddle or in a pan, until crisp, 2-3 minutes each. Or brush them with oil, lay them on a cookie sheet, and bake them in oven for 10-12 minutes, flipping once.
Spread bean mixture evenly over each tortilla. Toss arugula with remaining lemon juice, lemon zest and 1 tablespoon olive oil. Mound arugula on each tortilla, and top with remaining parmesan cheese and red pepper flakes, if you like.