Sous Vide Lamb with Rogan Josh-Style Sauce

Ingredients

• 500g (about 1 pound) lamb shoulder, cut into bite-sized pieces
• 2 tablespoons tandoori paste
• 3 tablespoons vegetable oil or ghee, divided
• 3/4 red onion, 1/4 minced and 1/2 chopped
• 1 large or 2–4 small chiles, chopped, plus 1 sliced chile, for serving
• 2 cloves garlic
• 2 teaspoons grated fresh ginger
• 1 teaspoon cardamom pods, ground
• 1 teaspoon coriander seeds, ground
• 1 teaspoon cumin seeds, ground
• 1 teaspoon paprika
• 1/2 teaspoon turmeric
• Salt
• 1 (14-ounce) can whole tomatoes
• 4 tablespoons tomato paste
• 1 cinnamon stick
• 3 tablespoons plain yogurt
• 2 tablespoons chopped fresh cilantro, for serving
• Rice, naan bread and/or papadums, for serving