In a saucepan, heat the olive oil and butter over medium heat. Add the chopped onion and minced garlic. Sauté until they become translucent.

Add the Arborio rice and stir to coat the rice with the oil and butter. Continue to cook for a couple of minutes until the rice becomes slightly translucent at the edges.

If using saffron, dissolve it in a small amount of hot stock. Add this saffron-infused stock to the rice and stir.

Gradually add the hot fish or vegetable stock, one ladleful at a time, stirring constantly and allowing the liquid to be absorbed before adding more. Continue this process until the rice is creamy and cooked to your desired level of doneness (usually around 18-20 minutes).

Stir in the diced lobster tails and halved cherry tomatoes. Cook for an additional 2-3 minutes until the lobster turns opaque and the tomatoes soften.

Remove from heat and stir in the grated Parmesan cheese. Season with salt and black pepper to taste.

Serve the lobster risotto hot, garnished with chopped fresh parsley.