Soak the barley and pulses (yellow split peas, green split peas, red split lentils, and blue peas if using) overnight in water to soften them.
In a large pot, heat some oil and sauté the diced onions until translucent.
Add in the soaked barley and pulses, carrots, and any other optional vegetables you're using. Stir well to combine.
Pour in enough stock to cover all the ingredients in the pot and bring to a boil.
Reduce the heat to a simmer and let the broth cook for about 1-2 hours, stirring occasionally. Add more stock if needed to reach your desired consistency.
If adding meat, include the ham hock or mutton at this stage and let it simmer in the broth until tender and flavorful.
Season with salt and pepper to taste, and adjust any additional seasonings as preferred.
Just before serving, stir in the chopped kale or greens for added color and nutrition.
Serve hot and enjoy your homemade Scotch Broth!