Soak the cashews. Place cashews in a bowl and cover with hot water. Leave to soak while you prep everything else (10–15 minutes). This gives your sauce a silky smooth texture.
Rinse and toast the buckwheat. Place buckwheat in a sieve and rinse under cold running water until it runs clear. Heat 1 tbsp olive oil in a medium saucepan over medium heat, add the buckwheat and toast for 2–3 minutes, stirring, until nutty and fragrant.
Cook the buckwheat. Add 480 ml water, broth powder or cube, smoked paprika, cumin, salt and pepper. Bring to a boil, reduce heat to low, cover and simmer for 15 minutes until tender and water is absorbed. Turn off heat and leave covered for 5–10 minutes. Fluff with a fork before serving.
Preheat oven to 200 °C (top/bottom heat) and line a large baking tray with baking paper.
Prep the vegetables. Peel onions, halve from root to tip and slice into thin wedges. Remove seeds and stem from bell peppers, cut into 2 cm strips. Scrub carrots, trim ends, slice into 1 cm half-moons. Cut broccoli into bite-size florets; peel the thick stalk and slice into 0.5 cm coins — don't waste it, it roasts beautifully.
Season and roast. Add all vegetables and drained white beans to the baking tray. Drizzle with 2 tbsp olive oil and vinegar, sprinkle over paprika, thyme, oregano, garlic powder, salt and pepper. Toss directly on the tray until everything is well coated and spread in an even layer. Roast for 20–25 minutes, tossing once halfway, until tender and golden at the edges.
Make the dill cream. Drain the soaked cashews. Blend cashews, plant milk, lemon juice, vinegar, mustard, garlic powder and salt until completely smooth. Add a splash more plant milk if needed to reach a thick but pourable consistency. Stir in the dill and taste — adjust salt and lemon to your liking.
Toast the sunflower seeds. Mix sunflower seeds with oil, smoked paprika and a pinch of salt. Spread on a small corner of the vegetable tray for the last 5–7 minutes of roasting, or toast in a dry pan over medium heat for 3–4 minutes, stirring constantly, until golden and fragrant.
Assemble. Divide the buckwheat between 4 bowls. Top with a generous portion of roasted vegetables and beans. Spoon 2–3 tbsp of dill cream over each bowl in soft ribbons. Finish with a sprinkle of smoky sunflower seeds, a grind of black pepper and a lemon wedge on the side.