Blend kosher salt, cumin, oregano, minced garlic, chili powder, 1 teaspoon ground black pepper, celery seed, and ground thyme together in a food processor.
Lay baby back rib slabs and sparerib rack on sheets of aluminum foil. Rub spice mixture all over ribs and fold aluminum foil up around each. Divide apple juice between each foil packet and fold foil edges together to form a seal. Marinate ribs 8 hours to overnight.
Set oven rack about 6 inches from the heat source and preheat the oven's broiler. Line a baking sheet with aluminum foil. Place jalapeno peppers, cut-side down, onto the prepared baking sheet.
Cook jalapeno peppers under the preheated broiler until the skin has blackened and blistered, 5 to 8 minutes. Place the blackened peppers into a bowl and tightly seal with plastic wrap. Allow the peppers to steam as they cool, about 20 minutes. Remove and discard skins.
Blend jalapeno peppers, beer, onion, strawberry preserves, barbeque sauce, olive oil, garlic cloves, sea salt, and pinch ground black pepper together in a blender until sauce is smooth. Transfer sauce to a container, cover with a lid, and refrigerate, 8 hours to overnight.
Preheat oven to 200 degrees F (95 degrees C). Place foil-wrapped ribs in a single layer on baking sheets.
Cook ribs in the preheated oven for 1 hour. Increase oven to 225 degrees F (110 degrees C) and continue cooking ribs until almost tender, 2 to 3 hours more.
Preheat smoker to 250 degrees F (120 degrees C).
Unwrap ribs, discard apple juice, and place ribs directly on the smoker.
Cook on the preheated smoker until meat surface is slightly dry, 5 to 10 minutes. Continue cooking, brushing sauce on ribs every 15 minutes and turning every 30 minutes, until tender, about 1 hour.