The cuisine of Rwanda is based on local staple foods produced by subsistence agriculture such as bananas, plantains (known as ibitoke), pulses, sweet potatoes, beans, and cassava (manioc). Many Rwandans do not eat meat more than a few times a month. For those who live near lakes and have access to fish, tilapia is popular. The potato, thought to have been introduced to Rwanda by German and Belgian colonialists, is very popular. Ubugari (or umutsima) is a paste made from cassava or maize and water to form a porridge-like consistency that is eaten throughout East Africa. Isombe is made from mashed cassava leaves and served with dried fish. Lunch is usually a buffet known as mélange, consisting of the above staples and sometimes meat. Brochettes are the most popular food when eating out in the evening, usually made from goat but sometimes tripe, beef, or fish. In rural areas, many bars have a brochette seller responsible for tending and slaughtering the goats, skewering and barbecuing the meat, and serving it with grilled bananas. Milk, particularly in a fermented yoghurt form called ikivuguto, is a common drink throughout the country. Other drinks include a traditional beer called urwagwa, made from sorghum or bananas, which features in traditional rituals and ceremonies. Commercial beers brewed in Rwanda include Primus, Mützig, and Amstel.