Caramelized Onions:

Start by slicing your onion lengthwise into four quadrants. Take each quadrant, one by one, and slice crosswise into thin "half-moons". Heat a castiron skillet over medium heat and add 2 tbsp butter.

Note: I prefer to use a castiron skillet for caramelizing, as it allows for a "fond" to build under the onions, which is where most of the flavour comes from.

Add the onions to the skillet and stir to coat evenly with butter. Let them cook, stirring periodically (every 5 minutes or so). Once they become a shade of "blonde" (approximately 20 minutes), start watching for the "fond". Make sure to let it build before scraping it off the bottom to mix, but avoid letting it burn. From this point on, it's up to you how dark you'd like your onions. The deeper in colour, the stronger the flavour. I typically stop the process around 40 minutes, but taste your onions as you go and stop when you're ready. If the pan starts to show burning, near the end, put a small about of water in to "deglaze". Once the onions are at the point that you like, add 1 tbsp of balsamic vinegar and mix. Remove onions from pan, and set aside for later.

Risotto:

Note: I prefer using a very wide/deep pan for risotto, instead of a pot. It allows for the risotto to cook more evenly, and helps to avoid overcooking the grains closer to the bottom.

Keep broth warm in a saucepan, over medium-low heat. Don't let it boil. In a large pan, heat 2 tbsp butter and 2 tbsp olive oil over medium heat. Once the butter is foaming, add the leeks. Let them sweat until slightly soft, about 2 minutes, and add garlic. Once fragrant, add arborio rice and stir to coat evenly in butter. Stir grains relatively frequently until slightly golden. Once the rice is toasted, pour in the white wine and mix until completely absorbed. 1/2 cup at a time, start adding the warm broth, stirring constantly until absorbed. From start to finish, this portion of the process takes approximately 20 minutes. If you'd like to add mushrooms to your risotto, you would do so once you've made it through half the broth.

Once the risotto has reached your desired consistency (creamy and al dente), fold in the freshly grated parmesan (I sometimes add a little extra), caramelized onions, lemon zest, and parsley (reserving some for garnish). Salt and pepper to taste, and you're ready to serve!