Put the garlic, onion, and olives in the bowl of a food processor and pulse until finely chopped (it’s important to stop before the mixture turns to a smooth puree).
Add the parsley and oregano and pulse briefly, 1 to 2 seconds, until the herbs are also finely chopped but not pureed. Or, if working by hand, finely mince the ingredients with a sharp knife and combine in a small mixing bowl.
Transfer the mixture to a medium bowl. Add the oil, lime juice, vinegar, paprika, sugar, cayenne, and red pepper flakes (or more to taste) and stir until the sugar dissolves. Season to taste with salt.
Pour ¼ cup of this marinade into a shallow, medium baking pan, reserving the rest.
Heat a stovetop or outdoor grill to high heat.
Spray the tofu pieces evenly with cooking spray on both sides. Grill them for about 1 to 2 minutes on each side, flipping them with a long spatula, until distinct hash marks form.
Transfer them to the baking pan, setting them atop the marinade and pouring the reserved marinade over.
Cover the pan and refrigerate for 8 to 12 hours (or up to overnight for more flavor).