In a skillet, combine the coriander and fennel seeds, peppercorns, crushed red pepper and bay leaf and cook over moderate heat, shaking the pan, until fragrant, 1 minute. Transfer the spices to a grinder and let cool. Add the paprika and finely grind the spices, then transfer them to a bowl and stir in the 1/2 cup of olive oil. Stir in the garlic paste.
Arrange the tofu in a baking dish. Spread all but 1 tablespoon of the spice paste over the tofu. Cover with plastic wrap and refrigerate for at least 4 hours or up to 48 hours.
Light a grill and oil the grates. Season the tofu with salt and grill over moderate heat, turning, until just heated through, 10 minutes.
Grill the buns until toasted. In a bowl, mix the mayonnaise and barbecue sauce with the remaining 1 tablespoon of spice paste. Spread the mayonnaise sauce on the buns and top with the tofu, lettuce, pickles, red onion and tomatoes. Close the sandwiches and serve.