In a large bowl, combine the minced beef, cauli-rice, chopped onion, minced garlic, egg, salt, pepper, Dijon mustard, parsley, and paprika.
Mix well until everything is evenly incorporated.
Set aside.
Bring a large pot of salted water to a boil. Carefully separate the 12 largest outer leaves from the cabbage.
Place them in the boiling water and blanch for 1 to 2 minutes, just until they become limp and pliable. Immediately transfer the leaves to a large bowl of ice water to stop the cooking process.
Once cooled, drain and pat them dry.
Prepare the slow cooker by finely slicing the remaining core and leaves of the cabbage and placing them in the bottom.
Pour the bone broth over the sliced cabbage to create a bed for the rolls.
Lay a blanched cabbage leaf on a flat surface. Use a paring knife to carefully shave down the thick part of the stem, making it more flexible without cutting through the leaf.
Place about 1/4 cup (70 g / 2. 5 oz) of the meat filling in the center of the leaf.
Fold in the sides, then roll the leaf up tightly from the bottom to create a secure parcel.
Place the roll seam-side down in the slow cooker.
Repeat with the remaining leaves and filling, arranging the cabbage rolls in two or three layers.
Cover and cook on low for 6 hours.
Shortly before serving, prepare the spicy hollandaise. Gently melt the butter in a small saucepan and set aside.
In a heatproof bowl, whisk together the egg yolks, lemon juice, water, and Dijon mustard.
Create a double boiler by placing the bowl over a saucepan of simmering water (ensure the water doesn't touch the bottom of the bowl).
Whisk the egg yolk mixture constantly until it begins to thicken.
While still whisking, slowly drizzle in the melted butter until the sauce is thick, creamy, and fully emulsified. If it becomes too thick, whisk in a splash of water.
Remove from heat and stir in the sriracha sauce.
Serve the warm cabbage rolls immediately, generously topped with the fresh spicy hollandaise sauce.
Don't overfill the leaves. This prevents them from bursting open during the long cooking time.
