Boil water in a saucepan and cook carrots until tender. (about 10 minutes)
While the carrots are cooking, heat skillet over high heat. Put mustard seed in the skillet and roast. When the mustard seeds start to splutter, cover and keep roasting until browned shaking the skillet constantly. Then grind the mustard seed in a blender or coffee blender. (or if you have mortar and pestle, those work too) Transfer to a bowl and add chili powder, cumin powder and salt to the bowl. Stir well.
In a clean jar or container, put carrots, spice mix, lemon juice and olive oil. Shake to coat well. Keep the carrots pickles in a warm room for 2-3 days.(shaking the jar/container once in a while) Then refrigerate until served.