Bean and Grain Stew with Garlic and Chiles

Heat a medium skillet, preferably cast iron, over medium-high until very hot. Carefully lay a piece of foil inside skillet, followed by onion, cut sides down. Char onion until totally blackened on cut sides, about 15 minutes. Wipe out skillet and reserve.

Transfer onion to a small pot. Add beans and enough water to cover them by about 2". Give everything a stir and bring to a boil over medium-high heat, then reduce heat and simmer, skimming off any foam and adding water if needed to keep beans submerged, until beans are tender, 1½–2 hours. Season with salt. Ideally, they should cool overnight in their cooking liquid, but they’ll still be awesome if you can’t hit pause at this point.

Meanwhile, cook grains in a large pot of boiling salted water until al dente, 50–70 minutes. Let cool in their liquid—ideally overnight, but same story as with the beans.

Preheat oven to 300°. Toss bread with ¼ cup oil on a large rimmed baking sheet. Season with salt. Squeeze and toss bread to absorb as much oil as possible. Bake until croutons are well-browned and very crisp, 35–45 minutes.

Meanwhile, combine chile and rice vinegar in a small bowl. Soak until ready to use.

Bring garlic and ½ cup oil to a simmer in a small saucepan over medium heat. Cook, lowering heat as needed to maintain a gentle simmer and swirling occasionally, until garlic is golden brown, 12–14 minutes. Using a slotted spoon, transfer garlic chips to paper towels. Reserve garlic oil.

Heat remaining 2 Tbsp. olive oil in reserved medium skillet over medium-high. Add mushrooms and cook, undisturbed, until browned underneath, about 2 minutes. Toss and continue to cook, tossing occasionally and adding kale a few pieces at a time, until mushrooms are browned and crisp and kale is just wilted, 5–6 minutes. Season with salt; transfer to a plate.

Transfer 2 cups grains (including some of their liquid) to a medium bowl; wipe out pot. Return grains and their liquid to pot. Add 4 cups cooked beans (including some of their liquid; discard onion). Bring to a simmer. Add red wine vinegar and ⅓ cup garlic oil. Season to taste with salt and pepper. Just before serving, chop half of mushrooms and kale and fold into stew. Add lemon juice, half of croutons, and half of garlic chips. Taste and add more lemon juice, if needed.

Divide stew among bowls and top with remaining mushrooms, kale, croutons, and garlic chips. Top with chives and drained chile slices. Drizzle with remaining garlic oil as desired.

Do Ahead: Beans and grains can be cooked 1 day ahead; let cool in their cooking liquid.