Wash the potato and sweet potatoes and halve lengthways. Put them into a large microwave-safe bowl with ½ a lemon in the center (make sure the lemon and the potatoes skin side down). Cover with plastic wrap and put into the microwave on full power for 15 minutes. On a cutting board, finely chop most of the cilantro and slice the chili. Check to see if the potatoes are cooked through. Then, place them on the cutting board. Crumble the feta cheese straight from the package right over potatoes. With a large knife start cutting into the feta and potatoes with large sloppy chops using the knife to turn mixture over, as well. Continue chopping and add the chili and cilantro. Start pouring olive oil over the mixture. Add sea salt to taste. Chop, turn and mix until you get the desired consistency. You can serve on the chopping board or transfer to a serving plate. Put remaining cilantro on the top as a garnish