Add the olive oil to a large saucepan set over medium heat.
Add the onion and the garlic to the oil and saute until tender.
Now that the onion and garlic are tender, add the Arborio rice and stir until it is coated.
Add the wine and cook until the wine is fully absorbed into the rice.
With the wine absorbed, turn the heat down to medium-low. Add 1 – 2 ladles of the warm chicken stock, stirring constantly as you pour.
Let the risotto simmer until the liquid has absorbed.
Then keep adding 1-2 ladles at a time, waiting for the liquid to absorb between ladle sessions. Keep ladle sessions going until you have used about 2/3’s of the stock.
With 2/3 of the stock absorbed, add in the shrimp pieces, scallops, corn and leeks. Let cook up for just a minute.
Now, continue adding the stock in ladled sessions, until the rice has become tender and the consistency creamy.
Stir in the remaining herbs and the diced tomatoes, simmering until you are satisfied with the done-ness.
Once the texture is to your liking, add the butter and season the risotto with salt & pepper, to taste.
Serve immediately. If it becomes too thick before serving, add a bit more of warm stock to thin it out.