Growing greens indoor requires a warm windowsill and not much patience. All seeds have a have growth timeline call Days To Maturity. This is listed in all seed catalogs, and tells you when to expect to begin your harvest of fully mature vegetables and fruits. When harvesting for micro and baby greens, that timeline is greatly reduced. Many greens can be harvested in as little as 8 days after planting. Baby greens somewhere around the 20 day mark and braising greens at 52 days. You can use a small plastic windowsill greenhouse, which when covered keeps humidity high and helps with sprouting. Also, the plastic trays that you see bedding plants in are a great choice. Cover them with plastic wrap and achieve the same greenhouse effect. You can also build an outdoor cold frame on a budget. Old double paned windows are fantastic for growing in winter. When placed against the side of a shed or house facing south, they creates a warm enough environment for these cold season crops to germinate
Crops suitable for this are: Lettuces, Spinach, Kale, Radish, Tatsoi, and Komatsuna. Also some vegetables that work well: Broccoli, Cauliflower, Cabbage, Beans (for bean sprouts).