Cook quinoa according to the instructions on the package. Let cool down.
Preheat the oven to 200 C. Lay salmon fillet on the baking tray, sprinkle with some lemon juice and olive oil, add salt and pepper to taste and bake for 20 minutes. Let cool down and cut into pieces 2-3 cm thick.
For the dressing combine olive oil, lemon juice and Dijon mustard.
Layer the ingredients into the jar in the following order (from bottom to top): dressing, sliced cucumbers, grated carrot, quinoa, salmon pieces, sesame seeds, baby spinach leaves.
When serving move the ingredients onto the plate and mix to combine with the dressing. Add salt and pepper to taste