For The Biggest Burst Of Pho Flavor, Give Your Aromatics A Good Char
"Charred" is often considered a synonym for "failure" in most recipes. However, it's an entirely different story when it comes to making Vietnamese pho (the broth base, specifically). You'll get a lot more flavors and a more complex aroma from your broth base by charring essential aromatics like onions, shallots, and ginger before adding them to the pot.
When you roast these ingredients, the sugar in them is caramelized. So, when you later simmer them in the broth, they release a lot more flavor that you'd miss out on if you skipped roasting. The charred bits will bring a smoky, slightly bitter aroma and taste that perfectly complements the overall flavor of the broth.
The traditional Vietnamese method is to roast them over a gas burner on a burner grate. You only need to cook them for two to three minutes, flipping them every few seconds to ensure all sides get toasty and fragrant.
If you don't have a gas burner, an oven will also work. Position your oven rack directly under the broiler. Place the onions (quartered) and ginger (halved) in an aluminum foil-lined baking tray and drizzle some vegetable oil on them to help with caramelization. Set the broiler to high and bake for around 15 to 20 minutes, pausing every four to five minutes to flip the ingredients. You'll know they're ready when all sides are beautifully charred and they become fragrant.
Don't forget to toast the spices
Making a pho broth base involves more than just throwing charred onions, shallots, and ginger into a steaming pot of bone broth. To add the extra oomph to the broth, Vietnamese use a special mix of spices called "ngũ vị hương" or the "five-spice blend," which includes cinnamon, star anise, cardamom, coriander seeds, and cloves. But they aren't just added as they are. Typically, they're given a quick toast in a hot pan to further draw out their superb flavors and scents.
Here's how you do it: First, preheat a dry pan on medium-low heat. Then, add the spices to the hot pan and toast them for about a minute or two. While toasting, gently stir the spices with a pair of chopsticks or a wooden spatula to prevent them from burning (charring in this case is, obviously, not good).
Once the spices are fragrant, turn off the stove and transfer them into a clean cloth bag, like an empty tea bag. When you're simmering your broth, drop the cloth bag with the toasted spices and the charred aromatics from earlier into the broth. We guarantee that you'll notice the aromatic and the spice mix working their magic right away just from the fragrance alone. Then, when you serve your homemade pho in a bowl, you'll find that it not only smells wonderful but also tastes so much better than regular ramen.