Preheat an oven to 400 F. Place a rack on a rimmed baking sheet and place scallops on here overnight (especially if they are frozen). This will allow them to thaw and dry out for the best sear.
The next day, toast pine nuts in a dry pan. Combine pine nuts with capers, chopped parsley, apple cider vinegar, olive oil and ⅛ tsp kosher salt. Mix well to combine.
In the meantime, remove green stems from the cauliflower head and set aside. Slice cauliflower head in half with stem intact to hold florets together. Slice 1 ½” thick slice from each half allowing the remaining florets to fall on the cutting board. Chop remaining florets into small pieces and slice cauliflower leaves into ¼” pieces.
Heat a large nonstick skillet over medium-high heat. Add 1 tbsp olive oil and swirl the pan. Add the cauliflower steaks and sear them well on the first side, about 3-5 minutes. Turning the heat down as necessary. Flip and repeat on the other side. Be sure to season them with ¼ tsp of kosher salt.
Add in the florets and leaves. Place pan in the oven to finish cooking about 10-12 minutes.
Heat a large nonstick skillet until very hot. Add 2 tbsp olive oil and swirl the pan. Season scallops with ¼ tsp kosher salt. Add the scallops and sear on the first side for 2-3 minutes. Don’t use a timer, just watch the edges of the scallops until they turn a dark golden brown.
Flip and cook on the other side.
Immediately add 1 tbsp of salted butter. Then tip the pan and use a spoon to bast the scallops until they are cooked through, this takes about 2-3 more minutes. To plate, add one cauliflower steak to each plate along with some florets and leaves. Add scallops and then top cauliflower steaks with capers and pine nut topping. Serve hot!