Seared tuna on risotto with samphire & tomatoes

For ➋
tuna:
1 lime (juice only) 
1 garlic clove (peeled & crushed)  
2 tbs olive oil      
sea salt & pepper (freshly ground) 
2 x 200 g tuna steaks
risotto:  
2 tbs olive oil 
200 g risotto rice
50 g leek, chopped  
20 cl white wine  
80 c fish fumet    
sea salt & pepper (freshly ground) 
10 cherry tomatoes  
150 g samphire 
1 tbs Parmigiano
1 lime (quartered)

Mix together the lime juice, garlic, olive oil and salt & pepper in a shallow dish. Add the tuna and turn over several times to coat in the marinade. Place in the refrigerator until required.
Heat the fish fumet.
Heat some olive oil. Add the leek. Cover and cook mildly on moderate heat for 10-15 m. 
Add the rice until coated in the oil.
Slowly add the wine, and stir it through the rice.
Add most of the fumet. Cover and cook on moderate heat for 10-15 m, depending on the rice. Add some more fumet if needed.
Meanwhile, half the cherry tomatoes, and bake them in some oil.
Bring some of the fumet to boil and cook the samphire for 2-3 m.
When the risotto is soft and creamy, add 1 tbs Parmigiano. Add the tomatoes and samphire. Cover and let stand for 1 m. Spoon the risotto on plates
Bake or grill the tuna for 1 m on each side. Cut the tuna in nice slices and add to the plates. Serve immediately with quartered lime.