Preheat the oven to 200C/180C Fan/Gas 6.
Scatter a handful of salt over a baking tray. Place the red and golden beetroots on the salted baking tray and bake for 45 minutes or until soft.
Allow the beetroots to cool before peeling and dicing into 2.5cm/1in cubes. Mix with the garlic and grapefruit segments in a bowl.
Mix together the the gin, juniper berries, olive oil and mustard to make a dressing.
Blanch the courgette in salted water for 2 minutes, then drain and refresh in cold water. Add to the beetroot salad and drizzle over the dressing. Mix well.
Rub the sea bass fillets with some olive oil and season with salt, pepper and a little grapefruit zest.
Heat a frying pan over a high heat and sear the fillets skin-side down for 5 minutes until crisp. Carefully turn the sea bass fillets over and fry for a further 1–2 minutes, or until completely cooked through.
Transfer the sea bass to serving plates and serve with the beetroot salad and garnish with the beetroot slices.