Heat olive oil in a large pan over medium heat. Add white radish and onion, and cook for about 10 minutes, stirring occasionally, until they begin to soften and lightly caramelize.
Add garlic and chili, and continue cooking for another 3–4 minutes, allowing the flavors to develop without burning the garlic.
Sprinkle in the walnuts during the last few minutes so they toast gently in the pan.
Remove from heat and immediately stir in white and black sesame seeds to preserve their crunch.
Serve warm on its own, alongside rice, or as part of a larger plate with greens or protein.
This dish can also be prepared in the oven at 180°C for about 20-25 minutes if preferred.