Preheat the oven to 200 degrees. Cut the fennel bulb lengthwise into one-centimeter wedges, keeping a bit of the core attached so they don't fall apart. Toss them on a baking sheet with two tablespoons of olive oil, the fennel seeds, the crushed garlic, salt, and pepper, and roast for twenty minutes. Then add the whole cherry tomatoes and roast for another ten minutes, until the tomatoes burst and their juices run over the fennel.
Rinse the quinoa in a fine-mesh sieve under cold water; this washes away the bitter saponin layer on the seeds. Cook it in plenty of salted water for twelve minutes until tender, drain, and let it steam, covered, for five minutes until the germs curl open.
Pat the sea bass fillets bone dry and lightly score the skin three times with a sharp knife. These scores prevent the fillet from curling up in the hot pan: the skin shrinks faster than the flesh, and without the scores, the fillet would curl upwards, preventing the center from making contact.
Heat the remaining olive oil in a frying pan until shimmering. Sear the fillets skin-side down for three to four minutes over medium-high heat, pressing down lightly for the first thirty seconds, and only flip them when the skin releases and is crispy. Flip, add the butter, and cook for another half a minute.
Spoon the quinoa onto a plate, top with the fennel and tomatoes, and place the fish on top. Drizzle with lemon juice and sprinkle with parsley.