1. Cut the avocado in half, remove the stone and scoop out the flesh.
2. In a small bowl, mash the avocado with a fork, and then add the lime juice, garlic and olive oil.
3. Season with salt and pepper and mix well.
4. In a small bowl mix together the red onion and red wine vinegar.
5. Toast the sourdough until slightly charred.
6. Divide the avocado between the 4 toasts, and then top with the smoked sturgeon, red onions, jalapeno and radishes. Garnish with coriander and drizzle with olive oil, then serve.