In a large skillet add the bacon, turn on heat to medium and slowly render, turning to cook evenly and do not burn. Remove when crispy and set aside. Save bacon grease for other use.
Seeds fresh jalapeños and dice. Dice red onion and juice half the lemon. Slice the Roma tomatoes. Slice the iceberg lettuce very thin and set aside.
Seed avocados and place in a bowl. Add lemon juice, jalapeno, red onion, salt and pepper to taste. Mash to combine, but keep chunky.
Divide the guacamole evenly over the tostada shells. Place two slices of bacon on top. Add shredded lettuce, lay two or three slice of Roma tomato on top and season with cracked fresh black pepper and kosher salt. Garnish with any leftover jalapeño, red onion and cilantro.