In a blender/food processor, add the lentils, half the onion (chopped), and the sun-dried tomatoes (softened in water for a few minutes). Add the soy sauce, garlic, olive oil, a pinch of salt (or two), pepper, and thyme.
Blend until fairly smooth, scraping down the sides as needed. If it won’t blend, add a small splash of water (don’t overdo it).
The mixture should be quite soft. To shape it, firm it up with breadcrumbs, adding 1 tbsp at a time. If it becomes too dry and crumbles, add a little water back.
Shape into balls and place on a baking tray lined with parchment paper.
Drizzle with a little oil and bake for 20–25 minutes, turning halfway.
While they bake, make the sauce: sauté half an onion in a little oil (with soffritto mix if you have it).
When the onion is golden, add the passata, lower the heat, cover, and simmer for 20 minutes, stirring occasionally.
When both are ready, let the meatballs cool briefly (they’re fragile at first), then add them to the sauce. Warm through and serve.