Soak the marrow bones overnight in salt water (1 tsp salt per cup of water) to remove any excess blood. Rinse them in clean water and pat them dry the next day.
Fire up your smoker to 300°F
Season the marrow bones with salt and pepper
Make the garlic butter by melting 4 tbsp of butter on a small pan over low heat. Remove from heat, mix in the minced garlic, and let it cool for about 5 minutes.
Spread the garlic butter over the bone marrow.
Line a baking sheet with aluminum foil and place the marrow bones on it.
Transfer the baking sheet to the smoker grates.
Let the bones smoke over indirect heat till they reach an internal temperature of 145℉. This should take about 40 minutes. The bones should turn darker in color, and the marrow should start to shrink away from the sides of the bone.
Remove the bones from the smoker and let them cool on a cooling rack for 5-10 minutes.
Use a bone marrow spoon or cheese knife to scoop out the marrow
Spread the smoked bone marrow onto toasted French bread, sprinkle some chopped parsley, and give it a good squeeze of fresh lime juice.