The key elements to success are a well-seasoned stock, making sure to “toast” the rice in the fat with the onions, and constant stirring for the twenty minutes it takes to cook the rice. You are trying to draw the starch out of the rice and have it bond with the broth to achieve a starch-thickened sauce that the rice sort of floats in.
Stirring the rice in the broth continuously is the only way to get that starch bonded with the broth so that you get the creamy starchy amalgamation a true risotto demands. You don’t have to stand there moving your arm in a circular motion for twenty minutes, but you should stand over the pot and give it a stir every thirty seconds or so.
Different risotto eating regions of Italy have different consistencies they look for in risotto, from wetter to drier, and I like my rice to be not too dry but more soft and creamy, the consistency of a really creamy rice pudding. But if you like it drier, add a little less broth, and if you like it wetter, add a little more.
Heat the oil and butter together in a large heavy bottomed pot over medium low heat until butter is melted. Add the onions and a pinch of salt and cook until onions are soft and translucent. Add the rice and stir continuously until the rice is chalky looking with a white dot visible in the center, about 5 minutes. (“Toasting” the rice in fat is a critical part of the technique for successful risotto and some Italian recipes call for you to keep it moving with the onions and fat for up to 10 minutes but I find 5 sufficient.)
Add strawberries and sugar, stir to combine, and cook a few minutes until strawberries start to wilt. Add the red wine and stir until the wine is absorbed. Add 1 cup of simmering broth and stir until mostly absorbed. Keep adding the broth in 1/2-cup increments, stirring and waiting to add more liquid until the risotto until the liquid is almost completely absorbed. Repeat until the rice is cooked, still firm but with no hard white dot in the center of the grain.
Add a final 1/4 cup of broth and stir. Add the cheese and more salt if the risotto needs it. Remove from the heat, cover, and let rest five minutes. Garnish with the optional garnishes (choose only one) and eat immediately.