Sprinkle steaks evenly with Dry Rub; press gently into both sides of steaks. Refrigerate 30 min. Meanwhile, mix mayo, cilantro, parsley and garlic; refrigerate until ready to use.
Heat oil in deep medium skillet. Add plantains, in batches; cook 3 min. on each side or until lightly browned on both sides. Use slotted spoon to remove plantains from skillet; drain on paper towel-covered plate. Flatten to 1/4-inch thickness; return to skillet. Cook 1 min. on each side or until golden brown on both sides; drain.
Heat large skillet on high heat. Add steaks; cook 1 min. on each side or until medium-well doneness.
Spread mayo mixture onto flat sides of plantains. Top 4 plantain slices with steaks, Singles and avocados; cover with remaining plantains, mayo sides down.