Preheat oven to 400°F. Line a baking sheet with parchment paper and set aside.: You will feel the kitchen change as the oven warms, a dry, warming hum that signals readiness. Setting parchment on the baking sheet prevents sticking and encourages even browning on the bottom of the meatballs. The oven at 400°F produces a hot ambient temperature that crisps the exterior while keeping the center tender. One common mistake is rushing to bake before the oven has fully reached temperature, which can lead to uneven browning; use an oven thermometer if yours runs cool.
In a small bowl, combine the ground flax and water. Give it a stir and let it sit for at least 5 minutes to “gel.”: As the ground flax seeds absorb the water , the mixture will thicken into a sticky gel that looks glossy and slightly translucent. This texture mimics eggs and binds the mixture, so patience here matters. If you skip the rest time, you may find the mixture too loose and the meatballs will be crumbly, so allow the full five minutes.
Set a medium sauté pan over medium heat. Add the olive oil and swirl it around. Add the diced onions to the pan and stir. Sauté the onions until slightly soft and translucent, about 5 minutes. Add the garlic and oregano to the pan and sauté for another minute. Finally, add the nutritional yeast, chili, onion powder, salt, and pepper to the pan and stir for about 30 seconds. Pour in their lemon juice and scrape up any browned bits on the bottom of the pan. Take the sauté pan off the heat and set aside to cool.: You will notice the olive oil shimmer and the onion soften, releasing a sweet aroma. When the garlic and oregano hit the pan, the scent becomes herbaceous and savory. The brief stir with nutritional yeast and spices amplifies that toasty umami, and the quick splash of lemon juice lifts everything and loosens any fond. Letting the mixture cool prevents the hot ingredients from softening the beans too much later. Avoid browning the garlic too long, as it will turn bitter.
In the bowl of a food processor fitted with the “S” blade, place the walnut halves and the oats. Pulse the walnuts and oats until you have a coarse meal. Transfer the meal to a large bowl.: You'll hear the motor pulsing the walnut and rolled oats , and visually you'll see a coarse crumb that still has visible nut bits. This texture is intentional, providing a pleasing nubbly bite. If you overprocess into a powder, the mixture will be too uniform and lose textural interest, so pulse in short bursts and check frequently.
Place the bowl of the food processor back on the motor base. Add the white beans to the food processor and pulse until they are ground up with a little bit of chunky bean bits still in the mix. Transfer the ground white beans to the large bowl with the ground walnuts and oats.: When pulsing the white beans , aim for a mix that is mostly mashed but retains some small bean fragments. The sound will change from loud motor whir to a more muffled buzz as the beans break down. These little chunks help with mouthfeel. Overprocessing into a smooth paste will leave you with an overly sticky interior, so stop while there is still a bit of texture.
To the large bowl, add the flax gel mixture, sautéed onion and garlic mixture, tamari, lemon zest, parsley, dill, and big pinches of salt and pepper. Using a spatula or your hands, mix until thoroughly combined. Pinch off a bit of the mixture and give it a taste. Adjust the seasoning if necessary.: As you fold ingredients together, you will notice the mixture becoming cohesive and slightly tacky from the flax gel . The aroma should be herby and citrus forward with toasty walnut notes. Tasting is key here; I often add a pinch more sea salt or a squeeze more lemon juice to balance. A common error is under seasoning, which makes the finished meatballs bland, so taste and correct before shaping.
Measure out 2 tablespoons of the white bean and walnut mixture per meatball and roll it into a ball. Once you’ve rolled out all of the mixture, place the meatballs on the lined baking sheet. Lightly brush all of the meatballs with olive oil and then slide the baking sheet into the oven.: Rolling by hand lets you sense the binder and moisture level, and the meatballs should hold without crumbling. The surface will be slightly tacky, and after brushing with olive oil they will glisten. The oil encourages a golden exterior in the oven. If the mixture feels too wet, chill it briefly; too dry a mix will crack, so aim for malleable consistency.
Bake the meatballs for 25 minutes, or until the tops have dried out a bit, the meatballs are firm, and the bottoms are browned. Serve the meatballs with pasta, on a platter with hummus and tahini sauce, or even in a grain bowl setup!: During baking you will smell the walnut toasting and the herbs perfuming the oven. The exterior should feel set and the bottoms will show warm brown spots when you lift one. This timing yields tender centers and crisp outsides. A common mistake is overbaking which makes interiors dry; watch for slight give when pressed lightly.
