Afghan kidney bean curry

Ingredients

• rice
• 2 cans kidney beans rinsed and drained
• 1 can plum tomatoes or four large fresh tomatoes diced with all their juices
• 1 mug of vegetable stock
• 2 red onions
• diced. Reserve a third for garnish
• 4 cloves garlic
• minced or finely grated.
• 2 tablespoons oil
• 1 tablespoon whole coriander seed
• 1 teaspoon whole cumin seed
• 1/2 teaspoon dried mint
• Freshly ground black pepper
• or to taste
• Salt to taste
• Small bunch fresh coriander chopped