Heat olive oil (2 tbsp) in a pot over medium heat. Add onion (1 whole), carrots (2 whole), and celery (2 stalks) with a pinch of salt. Cook 8-10 minutes until softened and lightly browned.

Light browning builds depth. If you rush this, the soup tastes flat. • Edges of onion turning translucent and faintly browned • Sweet onion aroma

Stir in garlic (4 cloves), cumin (1 tsp), and smoked paprika (1 tsp) for 30 seconds. Add tomato paste (2 tbsp) and cook 1 minute, stirring.

Blooming spices in oil wakes them up and prevents raw spice taste. • Tomato paste goes from bright red to deeper brick • Toasty spice aroma

Add diced tomatoes (28 oz), lentils, broth, and salt. Bring to a boil, then reduce to a simmer. Cook 30-35 minutes until lentils are tender.

A steady simmer cooks lentils evenly without breaking them down into mush. • Soup thickens slightly; lentils look plump • Tomato aroma becomes rounder and less sharp

Stir in lemon juice (1 tbsp). Taste and adjust salt. Drizzle a little olive oil (2 tbsp) into bowls if desired.

Acid at the end fixes blandness faster than more spice. • Soup looks slightly glossier after finish • Brightness lifts the whole pot