Clean the mushrooms with a brush instead of washing to avoid sogginess. Roughly slice the caps and stems. Dice the red onion and crush the garlic.
Toast the walnuts and pine nuts in a dry pan until golden, keeping them moving so they don’t burn.
Heat 3–4 tbsp olive oil in a large pan over medium heat. Add the onion and cook for 5–6 minutes until soft and caramelised, then add the garlic and cook 1–2 minutes more.
Add the mushrooms and thyme, plus a little more olive oil if needed. Cook for 8–10 minutes, stirring often, until the mushrooms release their liquid and start to brown.
Stir in the soy sauce and redcurrant jelly. Season with salt and pepper, and cook for 2–3 minutes to meld the flavours.
Transfer the mixture to a food processor with the toasted nuts. Blitz while drizzling in the remaining olive oil, one tablespoon at a time, until smooth. Scrape the sides regularly.
Taste and adjust seasoning — add more salt, pepper, or a squeeze of lemon if needed.
Spoon into jars or dishes, cover, and chill for at least 1 hour before serving.