White Bean & Caramelized Onion Soup

Recipe 5 minPreparation Time 40 minCooking Time
White Bean & Caramelized Onion Soup

White Bean & Caramelized Onion Soup

5 minPreparation Time 40 min Cooking Time

About this Recipe

Slices of caramelized onion add richness to this white bean soup without using a lot of fat — just a little olive oil to get them going. A few coriander seeds and a couple of sprigs of marjoram contribute aromatic complexity. Marjoram is sweeter than oregano (but often mistaken for it), with a distinctive woodsy-pine scent and a citrusy note, here complemented by lemon zest. Garnish each bowl with a sliver of a lemon wedge for bright acidity and a fresh hit of citrus aroma as soon as it’s served.

The Benefits

This soup combines two of the most nutritious foods you can eat — beans and kale. Beans are an excellent source of protein and fiber, which can help protect against diabetes and heart disease, as well as possibly some kinds of cancers. They’re also rich in potassium, iron, magnesium and B vitamins including folate. Kale has absorbable calcium, more per serving than whole milk, and Omega-3 fatty acids, not easy to find in plant sources, plus loads of vitamins C, A, and K.

Note: If you’re starting with dried beans, soak them in plenty of water (they expand as they hydrate) to which you’ve added a fat pinch of salt for several hours or overnight. Drain and rinse the beans, put them in a large pot, and cover with cold water. Bring to a simmer and cook until they are tender, 30 to 40 minutes. Drain.  


Serves 4 to 6
  • 2 Tbsp (30 ml) olive oil
  • 1 tsp coriander seeds
  • 1 yellow onion, halved and sliced about 1/4" (6 mm) thick
  • 1 pinch salt
  • 2 garlic cloves, finely chopped
  • leaves from 2 sprigs of marjoram, finely chopped
  • 1 lemon
  • 2 1/2 cups (485 g) cooked white beans such as cannellini
  • 1 quart (950 ml) vegetable broth
  • 1 1/2 cups (100 g) kale, chopped
  • 1 cup (65 g) radicchio, shredded (optional)
  • Freshly ground black pepper to taste


  1. Step 1
    In a Dutch oven or other large heavy-bottomed pot, heat the 2 Tbsp olive oil over medium-high heat. When the olive oil is hot and shimmering, add the coriander seeds. Sauté, stirring frequently, until fragrant, about 1 minute.
  2. Step 2
    Add the onions and reduce the heat to medium-low. Cook, stirring as needed so that they brown but don’t burn, until caramelized to a light-medium brown, about 30 minutes. Turn the heat to low if the onions start to get too dark. If they start to dry out, add a little of the broth.
  3. Step 3
    Add a pinch of salt, the garlic, and marjoram. Increase the heat to medium-high and cook until the garlic is fragrant, 1 to 2 minutes. Using a rasp-style grater, grate the zest of the lemon into the pot. Cut the lemon in half lengthwise. Squeeze in the juice of half a lemon and set the other half aside.
  4. Step 4
    Stir in the beans and broth. Bring to a simmer and add the chopped kale and radicchio (if using). Add 1 tsp salt and a few grinds of black pepper. Simmer until the greens are tender, about 3 minutes. Taste and adjust the seasoning with salt and pepper.
  5. Step 5
    Cut slivers from the remaining half lemon for garnish. Ladle the soup into bowls and garnish each with a drizzle of olive oil and a sliver of lemon. Serve immediately. Any leftover soup can be stored in a covered container in the refrigerator for up to 3 days, or in the freezer for up to 1 month.

Substitutions: You can use other white creamy beans such as Great Northern or canary. Mix up the greens. The optional Treviso radicchio adds its rich burgundy color. Use a little chopped rosemary instead of marjoram.

Level Up: Before you add the greens, transfer as much as half of the soup to a blender and puree, then pour it back to the soup pot, for a play on texture. Top each bowl of soup with a few buttered, toasted whole-grain bread cubes, or serve it with slices of buttered toast. If you have fresh herbs such as chopped fresh parsley or chives, sprinkle them into each bowl for garnish.