Make the spice blend: Mix all spices/herbs together until blended. Store in an airtight container and use on fish, poultry, pork, or beef. (Makes about 1/4 cup).

In a small bowl, whisk together the mayonnaise, yogurt, lime juice, and cilantro. Cover and refrigerate until ready to assemble the sandwiches.

Sprinkle both sides of each tilapia filet generously with the cajun spice blend, pressing gently to coat. Put the coated filets on a plate while you make the bacon.

Heat a large fry pan over medium heat and cook bacon until crisp. Remove the bacon from the pan, transfer to a paper towel-lined plate, and leave 1 tablespoon of bacon grease to the hot pan to cook the fish.

Add as many of the filets to the hot pan as can fit, and cook until the underside is crisp and browned, 3 minutes. Gently flip the filets and cook for 3 more minutes. Remove the filets to a clean plate. If any filets stand to be cooked, add a teaspoon of oil to the pan, swirl to coat, and cook for 3 minutes per side. You may consider lowering the heat to prevent burning.

Assemble the sandwiches by laying the hamburger buns on a clean work surface and smearing 1 tablespoon cilantro-lime mayo on the (face-up) top sides of each. On the bottom halves, layer a leaf of romaine, slice or two of tomato, 1 tilapia filet, and 1 slice of bacon (folded in half or cut in half to cover more area). Top with the mayo-smeared halves and serve immediately.