Preheat oven to 400°F (200°C). Halve the tomatoes crosswise, place cut-side up on a rimmed baking sheet, drizzle with 1 tablespoon olive oil and a pinch (about 1/4 tsp) of salt. Roast for 25–30 minutes until the edges caramelize and flesh collapses. Why: Roasting concentrates the tomato's sugars and acidity, producing deep, jammy flavor that will give the finished rice an intense tomato note without watery dilution.

While tomatoes roast, finely dice the onion and mince the garlic. Heat 1 tablespoon olive oil plus 1 tablespoon butter in a wide, heavy sauté pan or shallow pot over medium heat. Add the diced onion and a pinch of salt; cook, stirring occasionally, until golden and caramelized (about 12–15 minutes). Add the garlic in the last 60 seconds. Why: Gently caramelizing the onion develops natural sweetness and savory depth—a foundation for the rice—while adding garlic late prevents it from burning and becoming bitter.

When the onion/garlic are translucent and fragrant, add the rice and stir to coat every grain with fat. Toast the rice 90 seconds to 2 minutes—don't brown it, just a light sheen. Why: Toasting the rice seals the exterior lightly, adding a subtle nutty flavor and helping the final texture stay distinct and not gluey.

Pour the hot stock into the pan (all at once) and bring to a gentle simmer. Add 1 tsp sea salt and 1/4 tsp black pepper. Reduce to a low simmer, cover partially and cook for 15–18 minutes, stirring once or twice, until rice is tender but still has a slight bite (al dente) and most liquid is absorbed. Why: Using hot stock prevents temperature shock and keeps cooking steady; covering partially controls evaporation so the rice cooks through evenly. Long-grain rice will not release the starch the same way Arborio does, so cook with a gentle hand to keep grains separate while still allowing enough liquid to become creamy when finished with butter and cheese.

While the rice cooks, remove the roasted tomatoes from the oven. Reserve two larger halves for garnish and roughly chop the remaining roasted flesh. If there is excess juice on the tray, scrape it into a small bowl and skim out any large seeds. Why: Reserving a couple of visual pieces for plating keeps the dish elegant; folding the concentrated tomato flesh into the rice distributes flavor without watering the texture.

When rice is tender and most stock is absorbed, remove pan from heat. Immediately stir in the remaining 1 tablespoon butter and all of the grated Parmesan. Fold in the chopped roasted tomatoes and lemon zest (if using). Taste and adjust seasoning with salt and pepper. Why: Finishing off heat with cold butter and cheese (monté) emulsifies and creates a silky, glossy texture—this is the shortcut to a risotto-style creaminess without specialty rice.

Let the rice rest, covered, for 3–5 minutes to allow flavors to marry and the texture to set. While resting, crisp the reserved roasted tomato halves quickly in a hot skillet with a drizzle of olive oil, about 30–45 seconds per side, just to warm them and add a caramelized edge for plating. Why: Resting evens out moisture and allows seasonal aromatics to bloom; searing the reserved tomato adds contrast in texture and temperature.

Spoon the rice into warmed shallow bowls, top with the seared tomato halves, scatter torn basil leaves, and finish with a light grind of black pepper and an extra shave of Parmesan if desired. Serve immediately. Why: Warm bowls keep the rice at ideal temperature; the finishing touches add freshness (basil) and visual appeal.