Preheat your oven to 400°F for roasting the sweet potato.
Peel and dice the sweet potato into small cubes. Toss the cubes lightly with a pinch of salt and set aside.
Spread the sweet potato cubes on a small baking tray and roast in the oven for about 15 minutes, or until tender.
While the sweet potato is roasting, trim the ends of the green beans and steam or blanch them until just tender, about 3-4 minutes. Drain and set aside.
Finely mince the garlic clove.
Pat the cod fillet dry with a paper towel and season lightly with salt and pepper.
Heat a non-stick skillet over medium-high heat. Add the olive oil and swirl to coat the pan.
Place the cod fillet in the skillet and sear for about 3 minutes on each side until the exterior is golden and the fish is opaque in the center.
In the last minute of cooking, add the minced garlic to the pan with the cod to infuse its flavor without burning.
Plate the seared cod alongside the garlicky green beans and roasted sweet potato cubes. Serve immediately.