Heat a heavy-bottomed skillet or the base of your slow cooker on the stovetop over medium heat (if your slow cooker has a sauté function, use that). Add the oil and once shimmering, add cumin seeds, coriander seeds and mustard seeds. Toast 30–45 seconds until fragrant but not burnt. Add the diced onions and a pinch of salt; cook, stirring occasionally, until translucent and starting to brown, about 8–10 minutes. Add minced garlic and ginger; cook 1–2 minutes until fragrant.

Stir in tomato paste and cook 2–3 minutes, pressing it into the pan to caramelize slightly; this builds depth. Add crushed tomatoes and coconut milk; stir to combine. Add stock, brown sugar, salt and black pepper. Bring mixture to a gentle simmer on the stovetop for 3–4 minutes to marry flavors before transferring to the slow cooker insert (or keep in the slow cooker pot if using stovetop-to-slow-cooker unit).

Spice blend (whole and ground spices)

While the base is simmering, stir in ground spices: turmeric, ground cumin, ground coriander, garam masala, smoked paprika and red chili powder. Taste the sauce (it will be concentrated); adjust salt and heat as needed. If preferred, you can bloom the ground spices for 30 seconds in the hot oil at the start before adding tomato paste to deepen flavor.

Protein & vegetables (choose one or combine)

Add your chosen proteins and vegetables to the slow cooker. For chicken thighs: nestle the pieces into the sauce so they are mostly submerged. For chickpeas: stir them in. For potatoes, carrots and other root veg: ensure they are mostly covered in liquid for even cooking. If using paneer or tofu, add in the last 45–60 minutes to avoid over-softening.

Set slow cooker to Low and cook 4–5 hours, or High for 2–3 hours, until chicken is tender and reaches 165°F, or vegetables are fork-tender. For chickpeas and hearty vegetables, 4 hours on Low is recommended for best texture and flavor development.

About 30 minutes before end of cooking, check seasoning and consistency. If curry is too thin, remove lid and switch to High (or transfer to stove) and simmer to reduce. If too thick, add 1/4 to 1/2 cup stock or water and stir gently. If using paneer or tofu, add now and cook remaining 30–60 minutes.

Finishing and garnish

When cooking is complete, turn off the slow cooker. Stir in lemon or lime juice, optional fenugreek leaves (rub between your palms before adding to release aroma), and stir in yogurt or crema if using to add creaminess. Adjust salt, sugar and acid to balance the curry—a final squeeze of citrus brightens the flavors.

Ladle curry into bowls, garnish with chopped cilantro, and serve hot with rice, naan, or flatbreads.