Sima is a traditional Finnish drink that is basically hard lemonade...
In a large non-reactive pot (stainless steel or ceramic coated, NOT aluminum), boil 3 liters (+ 1 cup to allow for evaporation, spillage ect.) of water with 2-3 cups white sugar, brown sugar, honey or any combo thereof (more sugar = more alcohol). When dissolved, add 2-4 thinly sliced lemons (some folks carefully peel and add the zest, cut away and discard the pith and add remaining pulp. too much pith can cause bitterness). Let simmer covered 15-30 minutes to allow peels to release lemon oil. Pulp should be partly disintegrated, releasing lemon juice.
Cool to room temp. (75°f/25°c). Placing pot in a sinkful of cool water will speed the process. While cooling, fill a small jar or glass half way with room temp. tap water. Sprinkle enough yeast to cover water surface (baking yeast for traditional low alcohol [1-5%] method, champagne or wine yeast for high alcohol [8-18%]). Do not stir or shake... wait 10 min. or until all the yeasties have become moist and sunk to the bottom. Now add a small amount ( <1/2 tsp., just enough to wake them up) of sugar and stir. Let sit undisturbed until a foamy layer forms on top. When the yeast is going strong, add it to the lemonade. If after 1 hour or so, you don't see any sign of fermentation (ie; foamy layer) you may want to add baking soda (1/2 tsp. at a time) to de-acidify and repeat yeast step. Once fermentation has begun, cover and let sit for 24 hours.
Now it's time to bottle. You'll need bottles, a narrow tipped funnel, a small pitcher (easier to handle than large pot) and optionally, a small screen type strainer (Note: I like to strain mine to remove pulp and seeds but you don't have to. If you do use a strainer be sure the openings are big enough to let the yeasties pass through while catching the larger bits. Use wire screen type not plastic mesh type) I use 4 750 ml. screw top Torani bottles per batch. 2 liter soda bottles work as well, in which case you should make a 4 liter batch (adjust ingredients accordingly). IMPORTANT... be sure your bottles are very clean, contamination can cause off flavors or even make you ill.
Stir lemonade vigorously to get yeast evenly mixed in solution and pour into a pitcher. Place funnel in mouth of bottle and strainer in funnel. Fill bottle leaving a 2 inch air space at the top. (Note: The traditional method calls for adding 2-3 raisins to the bottle. Some claim this provides micro-nutrients that the yeast needs. I have found no difference with or without them and they only serve to clog up my straw when I drink it.) Repeat til all bottles are filled. Place the caps on slightly loose to allow the CO2 gas to escape. Store at cool to room temp. for anywhere from 2 days for kid friendly, very low alcohol [<1%] version to a month for the high alcohol, adults only version. Tighten caps 24-48 hours before serving (less if fermentation is still vigorous) to allow CO2 to make the drink fizzy. Serve cold.