Make the strawberry-rhubarb compote: in a saucepan, combine the rhubarb sections and the chopped strawberries. Add the lemon and heat over low / medium heat so that it stews quietly for 10 minutes. Mix frequently, the fruits should be soft.

In a bowl, mix the whole sugar and the cornstarch then add this mixture to the saucepan, do not stop stirring for 1 to 2 minutes while the mixture thickens. Stop cooking then let cool for the rest.

Preheat the oven to 175 ° traditional heat. In a bowl, combine all the crumble ingredients (except almonds): flour, oatmeal, baking soda, salt, sugars, soft butter and vanilla. Do not hesitate to mix with your hands: you should get a kind of coarse sand. Set aside about 1/3 of the mixture (for the top of the pie).

Butter and flour a 30x20cm rectangular mold (or line with baking paper), then press the crumble into the bottom of the mold, pressing firmly with your hands.

Cover this base with the strawberry-rhubarb compote and smooth.

Mix the remaining crumble and the slivered almonds then sprinkle the top of the mold with the crumble (making more or less large pieces).

Bake for 30 minutes or until the top is golden (watch out).

Let cool out of the oven then refrigerate before cutting the pieces.