Add Erwtensoep (Dutch pea soup) recipe (#438)

* Add Erwtensoep (Dutch pea soup)

* Update erwtensoep.md

src/erwtensoep.md

@@ -0,0 +1,47 @@
+# Erwtensoep (Dutch pea soup)
+
+Erwtensoep, also called snert, is the Dutch version of pea soup. 
+Slices of rookworst (smoked sausage) are added before serving. The soup, which is traditionally eaten during the winter, is emblematic of Dutch cuisine.
+It is customarily served with Frisian rye bread (roggebrood) and bacon, cheese or butter.
+Pancakes are sometimes served with pea soup; this dish is called snert met struif, struif referring to the pancakes.
+
+- ⏲️ Prep time: 15 min
+- 🍳 Cook time: 90 min
+- 🍽️ Servings: 4
+
+## Ingredients
+
+- 7 1/2 cups / 1.75 liters water
+- 1 1/2 cups / 300 grams peas (dried green split)
+- 3 1/2 ounces / 100 grams pork belly (Dutch speklapjes or thick-cut bacon)
+- 1 pork chop
+- 1 bouillon cube (vegetable, pork or chicken)
+- 2 ribs celery
+- 2 to 3 carrots (peeled and sliced)
+- 1 large potato (peeled and cubed)
+- 1 small onion (chopped)
+- 1 small leek (sliced)
+- 1 cup celeriac (cubed)
+- 1 pound sausage (chopped rookworst, smoked sausage)
+- Salt and pepper
+
+## Directions
+
+1. In a large soup pot, bring water, split peas, pork belly or bacon, pork chop, and bouillon cube to a boil.
+2. Reduce the heat to a simmer, cover and let cook for 45 minutes, stirring occasionally and skimming off any foam that rises to the top. 
+3. Remove the pork chop, debone, and thinly slice the meat. Set aside.
+4. Add the celery, carrots, potato, onion, leek, and celeriac to the soup.
+5. Return to the boil, reduce the heat to a simmer and let cook, uncovered, for another 30 minutes
+6. Add the smoked sausage for the last 15 minutes of cooking time.
+7. When the vegetables are tender, remove the bacon and smoked sausage, slice thinly, and set aside.
+8. If you prefer a smooth consistency, purée the soup with a stick blender.
+9. Season to taste with salt and pepper.
+10. Add the meat back to the soup, setting some slices of sausage aside.
+11. Serve in heated bowls or soup plates, garnished with slices of rookworst and chopped celery leaf. Enjoy!
+
+## Contribution
+
+- Thomas - [@Thomas05t](https://github.com/Thomas05t)
+- Rijk - [@rijkvp](https://github.com/rijkvp)
+
+;tags: dutch soup vegetables