Dice the onions. Set a pot over medium high heat, add the olive oil and the diced onions. Cook for about 10 minutes over low heat. Add diced garlic, peas and baking soda. Cook for about 15 minutes. Add the lemon zest, lemon juice and 2 cups of boiling water (500ml), season to taste.
Blend and serve
Transfer the pea soup to a blender, add fresh mint and blend until you get a velvety texture. Serve with sour cream, fresh mint or bread, grilled bacon or even poached fish.