Serving illustration. Nutrition is approximate; results vary with ingredients and equipment.
Equipment
- 3–4 qt (3–4 L) slow cooker with lid
- Scale, chopping board and knife
- Skillet if a browning step is listed; food thermometer for meat
Before you begin
Use metric weights for the most consistent result. US volumes are approximate; oven temperatures refer to a conventional oven unless stated otherwise.
- Use brown or green lentils; red lentils break down and give a different texture.
- The cooking time is a range: slow-cooker models, ingredient temperature and cut size change the result.
Make it work
- Tough meat or firm lentils: allow more cooking time and check again; the timer does not replace texture cues.
- Watery sauce: reduce a portion in a separate saucepan; do not leave poultry sitting warm while doing so.
Prep 20 min · Cook 360 min
Cooking time includes any listed browning. LOW-setting duration is an estimate; check doneness and tenderness before serving.
Ingredients
- 1 1/4 cups (250 g) dried brown or green lentils, rinsed
- 3 carrots (250 g), diced
- 3 celery stalks (150 g), diced
- 4 cups (960 ml) water
- 1 tsp (1 g) dried thyme
- 1 tbsp (15 ml) lemon juice
- 1 medium onion (150 g), finely diced
- 2 garlic cloves (6 g), finely chopped
- 1 can (14 oz / 400 g) crushed tomatoes
- 1/2 tsp (3 g) fine salt
- 1/4 tsp (0.5 g) ground black pepper
Step-by-step method
- Check the appliance
Use a 3–4 qt (3–4 L) slow cooker and follow its manufacturer’s fill guidance, commonly one-half to two-thirds full. This recipe is unsuitable for an oversized nearly empty cooker. Thaw any frozen meat fully in the refrigerator; begin with chilled ingredients, not frozen meat. - Prepare and load
Pick over and rinse brown or green lentils. Dice vegetables into 1/2-inch (1.3 cm) pieces. Add lentils, carrots, celery, onion, garlic, water and thyme to the cooker. Keep tomatoes, salt, pepper and lemon for the final stage so acid does not delay lentil softening. - Cook with the lid on
Cover and cook for 5–6 hours on LOW. Keep the lid closed apart from the specified finishing step. The LOW setting must be a cooking setting, not KEEP WARM. Do not use a delayed start with raw meat. - Check and finish
When lentils are tender with no chalky center, stir in tomatoes, salt and pepper and cook covered another 20–30 minutes within the listed range. Add lemon at serving. If lentils remain firm, continue cooking before adding acid. - Portion the meal
Stir well and divide into four portions. The soup thickens as it stands; dilute with hot water when reheating. - Cool leftovers safely
Turn off after serving. Transfer leftovers into shallow containers promptly, refrigerate within 2 hours, and do not cool the meal in the unplugged cooker. Reheat separately to 165°F (74°C); a slow cooker is not a reheating appliance.
Cook’s notes
Use brown or green lentils; red lentils break down and give a different texture. A four-serving slow-cooker meal with quantities for an ordinary home kitchen.
Storage & reheating
- Refrigerate in shallow covered containers within 2 hours, at 40°F (4°C) or colder; use within 3 days.
- Reheat cooked leftovers until the center reaches 165°F (74°C). Freeze suitable portions for up to 2 months for best quality; thaw in the refrigerator.
Allergens
Check all packaged ingredient labels for additional allergens and cross-contact.
Approximate nutrition
Per serving: 300 kcal · Protein 18 g · Carbohydrates 58 g · Fat 1 g.
Approximate per-serving estimates calculated from ingredient weights using USDA SR Legacy food-composition references and representative proxies. Brands, drained weights, cooking losses and portion sizes change the result; unlisted sides and toppings are excluded.