Toss the romanesco with half of the lemon juice, some olive oil and season with salt and black pepper. Put on a baking sheet and place into the oven. Roast until golden brown, about 10 minutes.
Coat a large saute pan with olive oil. Add the garlic and red pepper flakes and bring to medium heat. When the garlic has turned a lovely golden brown, 2 to 3 minutes, remove it from the pan and ditch it - it has fulfilled its garlic destiny!
Add the Brussels sprouts and toss to combine. Season with salt, and cook until the sprouts have wilted, 2 to 3 minutes.
Remove the lid, raise the heat to medium-high and let the sprout leaves brown and frizzle, about 5 minutes more. Taste and season with salt if needed.
Toss with the pomegranate seeds, roasted romanesco and remaining lemon juice.