Mix garlic, steak seasoning, smoked paprika, chipotle or cumin, hot sauce, Worcestershire sauce, and vinegar. Whisk in extra virgin olive oil. Place meat in shallow dish and coat evenly to marinade. Let stand 15 minutes.
Cut larger potatoes in half, leave very small potatoes whole. Place potatoes in a pot and cover with water. Bring to a boil and cook potatoes 12-15 minutes until tender.
Heat a grill pan or outdoor grill to high heat.
Cut leek in half lengthwise. Chop into 1/2" pieces. Place leeks in a big bowl of water and release all the dirt from them with a good wash, separating all the layers. Drain leeks in a colander.
Grill flank steak 6-7 minutes on each side.
Put a drizzle of EVOO into a hot nonstick skillet over medium high heat. Cook bacon 3-5 minutes until it begins to crisp and has rendered most of it's fat.
Add leeks to the skillet and cook 3-5 minutes more until the leeks are tender.
Drain potatoes and return them to the hot pot. Smash the potatoes with the chicken stock or broth.
Add the bacon and leeks to the potatoes and continue to smash. Carefully fold in tomatoes. Season with salt and pepper to your taste.
Remove flank steak from grill and let juices redistribute before slicing. Thinly slice meat on an angle, cutting the meat against the grain.
Serve sliced flank steak next to BLT potatoes and top potatoes with a dollop of sour cream, if desired.